Apparatus and method for reading indicia using charge coupled device and scanning laser beam technology

ABSTRACT

A scanning device for reading indicia of differing light reflectivity, including bar code symbols, has two parallel arrays of light emitters, such as lasers or light emitting diodes, for generating a scanning light beam to visually illuminate sequential portions of the indicia. Two parallel arrays of sensors, such as charge coupled or other solid state imaging devices, detect light reflected from portions of the indicia and generate an electrical signal representative of the spatial intensity variations of portions of the indicia. Each array is arranged transversely of the direction along which the symbol is scanned.

[0001] This application is a continuation-in-part of U.S. patentapplication Ser. No. 09/540,404, filed Mar. 31, 2000, now allowed, whichis a continuation of U.S. patent application Ser. No. 08/833,650, filedApr. 8, 1977, now U.S. Pat. No. 6,123,264, which is a division of U.S.patent application Ser. No. 08/269,170, filed Jun. 30, 1994, now U.S.Pat. No. 5,672,858.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention generally relates to an apparatus and methodoperative for electro-optically reading indicia having parts ofdifferent light reflectivity, for example, bar code or matrix arraysymbols, and, more particularly, to apparatus using both charge coupleddevice (CCD) technology and laser beam scanning technology for properlypositioning, orienting and/or aiming such apparatus and reading one ortwo-dimensional bar code symbols, and to a method therefor.

[0004] 2. Description of the Related Art

[0005] Various optical readers and optical scanning systems have beendeveloped heretofore for reading indicia such as bar code symbolsappearing on a label or on the surface of an article. The bar codesymbol itself is a coded pattern of indicia comprised of a series ofbars of various widths spaced apart from one another to bound spaces ofvarious widths, the bars and spaces having different light-reflectingcharacteristics. The readers and scanning systems electro-opticallytransform the graphic indicia into electrical signals, which are decodedinto alphanumerical characters that are intended to be descriptive ofthe article or some characteristic thereof. Such characters aretypically represented in digital form and utilized as an input to a dataprocessing system for applications in point-of-sale processing,inventory control, and the like. Scanning systems of this general typehave been disclosed, for example, in U.S. Pat. Nos. 4,251,798;4,369,361; 4,387,297; 4,409,470; 4,760,248; 4,896,026, all of which havebeen assigned to the same assignee as the instant application.

[0006] As disclosed in some of the above patents, one embodiment of sucha scanning system resides, inter alia, in a hand-held, portable laserscanning head supported by a user, which is configured to allow the userto aim the head, and more particularly, a light beam, at a target and asymbol to be read.

[0007] The light source in a laser scanner bar code reader is typicallya gas laser or semiconductor laser. The use of semiconductor devices asthe light source in scanning systems is especially desirable because oftheir small size, low cost and low voltage requirements. The laser beamis optically modified, typically by a focusing optical assembly, to forma beam spot of a certain size at the target distance. It is preferredthat the cross section of the beam spot at the target distance beapproximately the same as the minimum width between regions of differentlight reflectivity, i.e., the bars and spaces of the symbol.

[0008] The bar code symbols are formed from bars or elements typicallyrectangular in shape with a variety of possible widths. The specificarrangement of elements defines the character represented according to aset of rules and definitions specified by the code or “symbology” used.The relative size of the bars and spaces is determined by the type ofcoding used, as is the actual size of the bars and spaces. The number ofcharacters per inch represented by the bar code symbol is referred to asthe density of the symbol. To encode a desired sequence of characters, acollection of element arrangements are concatenated together to form thecomplete bar code symbol, with each character of the message beingrepresented by its own corresponding group of elements. In somesymbologies, a unique “start” and “stop” character is used to indicatewhere the bar code begins and ends. A number of different bar codesymbologies exist. These symbologies include UPC/EAN, Code 39, Code 128,Codabar, and Interleaved 2 of 5, etc.

[0009] For the purpose of our discussion, characters recognized anddefined by a symbology shall be referred to as legitimate characters,while characters not recognized and defined by that symbology arereferred to as illegitimate characters. Thus, an arrangement of elementsnot decodable by a given symbology corresponds to an illegitimatecharacter(s) for that symbology.

[0010] In order to increase the amount of data that can be representedor stored on a given amount of surface area, several new bar codesymbologies have recently been developed. One of these new codestandards, Code 49, introduces a “two-dimensional” concept by stackingrows of characters vertically instead of extending the barshorizontally. That is, there are several rows of bar and space patterns,instead of only one row. The structure of Code 49 is described in U.S.Pat. No. 4,794,239, which is incorporated herein by reference. Anothertwo-dimensional symbology, known as “PDF417”, is described in U.S.patent application Ser. No. 461,881, now U.S. Pat. No. 5,304,786. Stillother symbologies have been developed in which the symbol is comprisedof a matrix array made up of hexagonal, square, polygonal and/or othergeometric shapes. Prior art FIGS. 24A-24C depict exemplary known matrixand other type symbols. Such symbols are further described in, forexample, U.S. Pat. Nos. 5,276,315 and 4,794,239. Such matrix symbols mayinclude Vericode(TM), Datacode(TM) and UPSCODE(TM).

[0011] In the laser beam scanning systems known in the art, the laserlight beam is directed by a lens or similar optical components along alight path toward a target that includes a bar code or other symbol onthe surface. The moving-beam scanner operates by repetitively scanningthe light beam in a line or series of lines across the symbol by meansof motion of a scanning component, such as the light source itself or amirror, disposed in the path of the light beam. The scanning componentmay either sweep the beam spot across the symbol and trace a scan lineor pattern across the symbol, or scan the field of view of the scanner,or do both.

[0012] Bar code reading systems also include a sensor or photodetectorwhich functions to detect light reflected or scattered from the symbol.The photodetector or sensor is positioned in the scanner in an opticalpath so that it has a field of view which ensures the capture of aportion of the light which is reflected or scattered off the symbol isdetected and converted into an electrical signal. Electronic circuitryor software decode the electrical signal into a digital representationof the data represented by the symbol that has been scanned. Forexample, the analog electrical signal operated by the photodetector maybe converted into a pulse width modulated digital signal, with thewidths corresponding to the physical widths of the bars and spaces. Sucha digitized signal is then decoded based upon the specific symbologyused by the symbol into a binary representation of the data encoded inthe symbol, and subsequently to the alphanumeric characters sorepresented.

[0013] The decoding process in known bar code reading systems usuallyworks in the following way The decoder receives the pulse widthmodulated digital signal from the bar code reader, and an algorithmimplemented in software attempts to decode the scan. If the start andstop characters and the characters between them in the scan were decodedsuccessfully and completely, the decoding process terminates and anindicator of a successful read (such as a green light and/or an audiblebeep) is provided to the user. Otherwise, the decoder receives the nextscan, performs another decode attempt on that scan, and so on, until acompletely decoded scan is achieved or no more scans are available.

[0014] Such a signal is then decoded according to the specific symbologyinto a binary representation of the data encoded in the symbol, and tothe alphanumeric characters so represented.

[0015] Moving-beam laser scanners are not the only type of opticalinstrument capable of reading bar code symbols. Another type of bar codereader particularly relevant to the present invention is one whichincorporates detectors based upon charge coupled device (CCD)technology. In such prior art readers the size of the detector istypically smaller than the symbol to be read because of the imagereduction by the objective lens in front of the CCD. The entire symbolis flooded with light from a light source such as light emitting diodes(LED) in the reader, and each CCD cell is sequentially read out todetermine the presence of a bar or a space.

[0016] The working range of CCD bar code scanners can be rather limitedas compared to laser based scanners and is especially low for CCD basedscanners with an LED illumination source. Other features of CCD basedbar code scanners are set forth in parent applications Ser. Nos. 317,553and 717,771 which are hereby incorporated by reference, and which areillustrative of the earlier technological techniques proposed for use inCCD scanners to acquire and read two-dimensional indicia.

[0017] It is a general object of the present invention to provide animproved indicia scanner without the limitations of prior art readers.

[0018] It is a further object of the present invention to provide anindicia scanner capable of providing the features of both a flying spotlight beam scanner and an imaging scanner in a single unit.

[0019] It is a still further object of the present invention to providea scanner for reading both two-dimensional or more complex indicia andlinear bar codes.

[0020] It is yet another object of the invention to provide a handheldindicia reader that is capable of aiming or being oriented and alsoimaging the field of view.

[0021] It is still another object of the invention to both perform laserscanning and CCD imaging either simultaneously, alternatively, or on atime-division multiplexed basis.

[0022] It is also an object of the invention to provide an indiciareader capable of automatically and adaptively reading indicia ofdifferent symbology types, including indicia comprised of a matrix arrayof geometric shapes such as a UPSCODE(TM), in close spatial proximity.

[0023] It is an even further object of the invention to provide a methodwhich can be used to accomplish one or more of the above objectives.

[0024] Additional objects, advantages and novel features of the presentinvention will become apparent to those skilled in the art from thisdisclosure, including the following detail description, as well as bypractice of the invention. While the invention is described below withreference to preferred embodiments, it should be understood that theinvention is not limited thereto. Those of ordinary skill in the arthaving access to the teachings herein will recognize additionalapplications, modifications and embodiments in other fields, which arewithin the scope of the invention as disclosed and claimed herein andwith respect to which the invention could be of significant utility.

SUMMARY OF THE INVENTION

[0025] According to the present invention a scanning device for scanningor reading indicia of differing light reflectivity, such as bar code ormatrix array symbols containing optically encoded information, isprovided. The scanning device has a single light emitter, preferablyincluding a laser or light emitting diode, for generating a scanninglight beam to visually illuminate sequential portions of the indicia andproduce reflected light from the indicia. A sensor, such as a lineararray of a charge coupled device or two-dimensional array of a solidstate imaging device simultaneously detects light from the light beam orambient light reflected from portions of the indicia and generates anelectrical signal representative of the reflected light from theportions of the indicia. The sensor may operate in either a scanning ornon-scanning mode, the latter being similar to that of a singlephotodetector, or in both modes. When operating in a scanning mode, thesensor may scan a field of view at a rate faster or substantially slowerthan the scanning light beam. The sensor may be controlled to scan afield of view only periodically and may function as a range detector todetect the distance between the scanning device and targeted indicia.The sensors' operation as a range detector is further described below.The emitter and sensor may be disposed in a hand-held housing to allowfor portable operation.

[0026] According to other aspects of the invention, the scanning devicemay also include an ambient light sensor for detecting the level of theambient light in a field of view and producing an output signal if theambient light is above a threshold value, i.e. the value at whichsufficient ambient light exist for a satisfactory read of the indiciawithout additional light being reflected from the indicia. An activatorcan also be included to activate the emitter, preferably automatically,in response to the output signal. The activator may also be responsiveto the electrical signal generated by the sensor. In this way, theemitter is activated, for example, only after the sensor has obtained asatisfactory read on one symbol and the emitter continues to emit alight beam until the sensor has obtained a satisfactory read of the nextsymbol. Unlike some prior art bar code readers, the light beam need notbe deactivated after a successful decode of a symbol. More particularly,the light beam could be deactivated only if no decode had taken placeafter a predetermined time.

[0027] A processor for processing the electrical signal is alsopreferably provided. The processor typically includes an analog todigital converter for converting the electrical signal into acorresponding digital signal, and a decoder for decoding the digitalsignal in order to obtain the information encoded within the symbol. Theprocessor may include a discriminator for determining whether thetargeted symbol is a linear or multidimensional symbol, or a bar codesymbol of a certain symbology type. A selection device is beneficiallyprovided for deactivating the light emitter if it is determined that thetargeted symbol is a multidimensional bar code symbol. The discriminatormay be adapted to more generally discriminate between indicia ofdifferent symbology types or to discriminate between indicia of anydesired symbology types. For example, the discriminator may be adaptedto look for symbols conforming to UPSCODE (TM). The sensor can beadapted to detect visible light reflected from a portion of the symbolwhich is formed of a bull's eye mark. Such marks are being morefrequently used in conjunction with symbols formed of a matrix array ofgeometric shapes, such as those conforming with UPSCODE(TM) symbology.

[0028] In a second embodiment of the invention for reading indicia ofthe types described above, a scanning device is provided with a firstlight emitter, for example a light emitting diode, which generates alight beam directed along a path toward the indicia, say a bar codesymbol, so as to illuminate a field of view including the indicia. Asecond light emitter, such as a laser diode, generates a scanning lightbeam to visually illuminate sequential portions of the symbol so as toproduce reflected light from the indicia. A sensor, preferably a linearcharge coupled or two-dimensional solid state imaging device, senses orimages the reflected light and generates an electrical signal responsiveto the detected light indicative of the indicia. The light from thefirst light emitter is thus used only for aiming or orienting thescanning device. If desired, the first and second light emitters can bedisposed in the same housing. The linear charge coupled device isbeneficially arranged within the scanning device so that the elongateddimension of the charge coupled device is parallel to the scanning lightbeam.

[0029] According to other aspects of this second embodiment, a ambientlight sensor identical in function to that described above may also beprovided. An activator to activate one or both of the light emittersresponsive to the output signal of the ambient light sensor isbeneficially included as part of the scanning device. The activator mayalso be made responsive to the electrical signal, as discussedpreviously in the context of the first embodiment. The scanning devicemay also include a processor like that described above, includingconverter, decoder, discriminator, selection device and other featuresof the processor described above. The sensor can, likewise, be adaptedto detect visible light reflected from a portion of the symbol which isin the form of a bull's eye mark.

[0030] In accordance with yet another embodiment of the invention, ascanning device for reading indicia, such as that previously described,having parts of different light reflectivity has a light source, such asa laser or light emitting diode, for generating a visible light beam. Anoptical element, preferably a mirror, directs the visible light beamsuch that a scan line is formed across the indicia. A sensor, preferablya charge coupled or other solid state imaging device, which includes anarray of detection elements, images the reflection of light from theindicia, for example visible light from the visible light beam orambient light, or a combination of the two, and generates an electricalsignal representing the reflection of the light from the indicia or,stated another way, the spatial intensity variations of the indicia. Theindividual detection elements can be scanned at a variable scanning rateif desired. An actable controller can be provided to change the elementscanning rate as desired. The scanning device may also include anintegrator for processing the output of the individual detectionelements to produce a single output signal. Preferably, auto-focusoptics to receive the reflected light and adjust the focal point of theimage on the array of detection elements are also provided. Processingcircuitry for processing an electrical signal generated by the sensormay be provided. The circuitry may include a determining means whichdetermines if the targeted indicia is a matrix code or bar code symbol,or of other differing symbology types, such as a linear ormultidimensional symbol. A selection means deactivates the light emitterand/or the sensor if it is determined by the determining means that thesymbol is of a particular symbology type, for example a bar code ofcertain symbology category.

[0031] This embodiment is particularly suitable for reading indicia,such as a bar code symbol, located within a range of approximately fourto ten inches from the scan head of the scanning device. The lightsource, optical element and sensor can be beneficially housed in a lightweight portable housing. The housing may also include an actuablecontroller as well as a wireless transmitter for transmittinginformation to a remote receiver.

[0032] The scanning device in accordance with this later embodiment mayalso include any or all of the other features, or be adapted to performany or all of the other functions, discussed above in connection withthe other described embodiments of the invention.

[0033] Additionally, in accordance with other aspects of this laterembodiment, a photodetector, such as a photodiode, for detecting thereflection of light from the visible light beam off the indicia may beprovided. With the photodetector incorporated in the scanning device,the sensor is beneficially used to detect either ambient light or lightfrom the light beam reflected off one portion of the indicia, or isutilized to estimate the distance or range between the radii and thetarget, while the photodetector is used to detect light from thescanning light beam reflected off another portion of the indicia. Suchan arrangement is particularly beneficial when the indicia is comprisedof two adjacent or otherwise proximately located symbols. For example,the sensor may be used to detect reflected light from a matrix arraysymbol, perhaps one conforming to UPSCODE(TM), and he photodetector usedto detect a one dimensional bar code symbol.

[0034] According to still further aspects of this later embodiment, thescanner can be adapted to operate in two or more distinct modalities,for example one for reading symbols of one symbology type such asstacked or other adjacent rows of linear bar codes, and the other forreading symbols of a different symbology type, such as matrix codes.

[0035] If two modalities are required, the scanner preferably includestwo symbol discriminators one of which is adapted to determine if thesymbol is of one predetermined category or symbology type and the otheradapted to determine if the symbol is of another predetermined category.A signal is generated by one symbol discriminator if the symbol beingimaged by the sensor does not conform to one of the symbology types. Thesensor is deactivated in response to this signal. A signal is generatedby the other symbol discriminator if the symbol detected by thephotodetector does not conform to the other of the symbology types. Thephotodetector is deactivated in response to this signal. By directingboth the sensor and photodetector to the same targeted symbol, thecategory of the targeted symbol is thereby indicated, since the symbolnecessarily conforms to the predetermined symbology type acceptable tothe symbol discriminator which does generate a signal to deactivate itsassociate detector. If both discriminators generate signals then thecategory of the targeted signal is necessarily outside the or determinedcategories for the scanner. Either of the two modalities are thereforeautomatically selected in response to a signal received from one of twosymbol discriminators. Thus, for example, in one modality a chargecoupled device is activated to read matrix codes by imaging and in theother modality a photodiode is activated to read bar codes using lightfrom a flying spot light beam or laser line reflected off the symbol.

[0036] In accordance with still other aspects of the invention asembodied in this later embodiment, the same sensor or, a second sensoris provided for ranging. The sensor senses the change in the imageproduced by the scanned visible light beam as the separation distancebetween the indicia and the scanning device is increased or decreased.The sensor also generates an electrical signal indicative of theseparation distance. Preferably the sensor is a position sensitivesensor or an array of detection elements.

[0037] In accordance with the scanning method of the present invention,a scanning light beam, preferably a visible laser light beam, isgenerated by a single light source to visually illuminate sequentialportions of the indicia in order to produce reflected light from theindicia. The light reflected from portions of the indicia, which may beambient light or light from the light beam, is simultaneously sensedpreferably using an imaging technique. The sensing may include detectingvisible light reflected from a portion of the indicia which is in theform of a bull's eye mark. The sensing may be performed onlyperiodically. Additionally, ranging may also be performed to determinethe distance to indicia. An electrical signal representative of thedetected light reflected from the portions of the indicia is generated.

[0038] According to other aspects of the inventive method, the level ofthe ambient light in a field of view is detected and an output signal isproduced if the ambient light is above a threshold value. The light beamis generated responsive to the output signal. Beneficially, the lightbeam can also be generated responsive to the electrical signal.

[0039] The electrical signal may be processed to obtain an indication ofthe type of indicia being scanned. Thus, the processing may include afirst threshold of determining whether the indicia is a linear ormultidimensional symbol, or a bar code symbol of a particular symbologytype, and generating the scanning light beam only if the bar code symbolis determined to be a linear bar code symbol. The processing can alsoinclude generating and processing a digitized signal corresponding tothe electrical signal. The processing may include discriminating betweenindicia of different symbology type's, linear, two-dimensional orstacked bar codes, matrix codes, or other types of indicia patterns.

[0040] According to another method of the present invention, two lightbeams are generated. One of the beams is directed so as to illuminatethe entire indicia simultaneously and produce first reflected light fromthe indicia. The other beam, preferably a laser light beam, is directedso as to scan the field of view, that is, to visually illuminatespatially sequential portions of the indicia and produce secondreflected light from the indicia. The two light beams may be directed todifferent parts of the target so that the reflected light from eachdistinct part can be distinguished. Alternatively, if the target area issmall, the two light beams can be time division multiplexed, so thatonly one beam is active at a given time. The first reflected light issensed, preferably by an imaging technique, and an electrical signal isgenerated representing the sensed light. The sensing or imaging mayinclude detecting visible light reflected from a portion of the indiciawhich is in the form of a bull's eye mark. The light from the secondbeam, i.e. the scanned beam, may be detected by a single detector, orthe same sensor used to detect the first beam, except the sensor is notoperated in the scanning mode.

[0041] According to other beneficial aspects of this second method, thelevel of ambient light in a field of view is detected and an outputsignal is produced if the detected ambient light level is above athreshold value. Either or both light beams are, as desired, generatedor modified responsive to the output signal. The electrical signal maybe processed to obtain information represented by the indicia. It mayalso be desirable for the light beams to be generated responsive to theelectrical signal. Processing typically includes converting the analogelectrical signal into a corresponding digital signal and decoding thedigital signal. The processing can, if desired, include discriminatingbetween indicia of different symbology types.

[0042] In a third method according to the present invention, a visiblelight beam, preferably a laser light beam, is generated and directedsuch that it forms a scan line across said indicia. The indicia issensed, preferably using an imaging technique, so as to sense areflection of light from the indicia. The detected light may be, forexample, reflected ambient light or visible light from the light beam.The sensing may include detecting light reflected from a portion of theindicia which is in the form of a bull's eye mark. One or moreelectrical signals representing the reflection of the light from theindicia is generated. If multiple electrical signals are generated, itmay be desirable to process these signals to produce a single outputsignal. It may also be beneficial to focus, automatically, the lightreflected from the indicia prior to sensing. This method is particularlysuitable for reading indicia within a range of approximately four to teninches from the scanning device. Preferably, signals corresponding tothe electrical or output signal are transmitted by a wirelesstransmitter or transceiver to a remote receiver or transceiver.

[0043] According to other aspects of the third inventive method, ambientlight levels in a field of view are detected and an output signalgenerated if the detected ambient light is above a threshold value. Thelight beam is generated in response to the output signal. The electricalsignal is typically processed. Processing can include converting theanalog electrical signal to a corresponding digital signal, and decodingthe digital signal to obtain optically encoded information representedby the indicia. The decoding may include discriminating between indiciaof different symbology types, for example, a bar code and a matrix arrayof geometric shapes, such as a UPSCODE(TM). It may also be beneficial togenerate the light beam responsive to the electrical signal so thatactivation occurs only when necessary and appropriate for obtaining aread.

[0044] In accordance with further aspects of the third method of theinvention, the reflection off one portion of the indicia of light fromthe visible light beam is photodetected while reflection off anotherportion of the indicia of either ambient light or light from the lightbeam is sensed. This method is particularly beneficial for use withindicia which include two symbols, for example a bar code and a matrixarray symbol, disposed adjacent or in close proximity to each other.

[0045] According to still other aspects of the third method of thepresent invention, the scanner or reader operates in two distinctmodalities, one for reading symbols of one symbology type or category,such as bar code symbols and the other reading symbols of a differentsymbology type or category, such as matrix codes. The scanner determinesif the symbol being targeted is of one of the predetermined category orsymbology types. A signal is generated which indicates the category ofthe targeted symbol and the modality is selected in response to thegenerated signal to subsequently read a symbol. Either of the two, ormore, modalities can be selected in response to the generated signal. Inone modality a charge coupled device may read matrix codes by imagingand in the other modality bar codes, such as stacked bar codes oradjacent rows of linear bar codes, may be read using light from a flyingspot light beam or laser line reflected off the symbol or indicia.

[0046] According to still further aspects of this third method, rangefinding is performed. Range finding is accomplished by sensing thechange in an image produced by the visible light beam while increasingor decreasing of the separation distance between the indicia and thescanning device. An electrical signal can then be generated which isindicative of the separation distance.

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] FIGS. 1A-1E are respectively (1) a side sectional view of agun-shaped, narrow-bodied, twin-windowed embodiment of a lasertube-based portable laser scanning head, (ii) a top sectional view of adetail of the laser tube and part of the optical train of FIG. 1A, (iii)a rear sectional view as taken along line IC-IC of FIG. 1A, (iv) a topplan section view showing the laser tube and part of the optical train,and (v) a front elevative view of the FIG. 1A embodiment, in accordancewith this invention.

[0048]FIG. 2 is a front perspective view of the FIG. 1 embodiment, on amuch smaller scale, and diagrammatically shows the interconnection ofthe head to the remainder of the scanning system.

[0049]FIG. 3 is a side schematic view of a gun-shaped, narrow-bodied,twin-windowed embodiment of a light-based portable scanning head inaccordance with this invention.

[0050]FIG. 4 is a top plan schematic view of the embodiment of FIG. 3.

[0051]FIG. 5 is a front view of a portable laser diode scanning head inaccordance with a second embodiment of this invention.

[0052]FIG. 6 is an enlarged cross-sectional view of the head of FIG. 5.

[0053]FIG. 7 is a sectional view taken on line 7-7 of FIG. 6.

[0054]FIG. 8 is an enlarged view of a symbol and the parts thereof whichare impinged upon, and reflected from, by a light beam.

[0055]FIG. 9 is a schematic view of a static single beam aimingarrangement.

[0056]FIG. 10 is an enlarged view of a symbol and the parts thereofwhich are illuminated by static single-beam, or by twin-beam aiming.

[0057]FIG. 11 is a schematic view of a static twin-beam aimingarrangement.

[0058]FIG. 12 is an enlarged view of a symbol and the parts thereofwhich are illuminated by a dynamic single-beam aiming.

[0059]FIG. 13 is a block diagram of the scanning system according to thepresent invention.

[0060]FIG. 14 is a flow chart of the operation of an algorithm used inthe present invention.

[0061] FIGS. 15A-15C are perspective views of a further embodiment of ahybrid scanner according to the present invention.

[0062] FIGS. 16A-16B are respectively a plan and elevation view of thehybrid scanner of FIG. 15A.

[0063]FIG. 17 depicts the scan line formed across a bar code symbolusing the hybrid scanner of FIG. 15A.

[0064] FIGS. 18A-18D are schematic representations of the range finderin accordance with the present invention.

[0065]FIGS. 19A and 19B are respectively a simplified side sectionalview and perspective view of the hybrid scanner of FIG. 15A, 15B or 15Choused in a narrow bodied, single windowed, gun-shaped housing.

[0066]FIG. 20 depicts a goose head type housing for a hybrid scanner ofFIG. 15A, 15B or 15C.

[0067] FIGS. 21A-21C depict a tunnel type scanner arrangement usingmultiple hybrid scanners of FIG. 15A, 15B or 15C.

[0068]FIG. 22 depicts a truck mounting arrangement using multiple hybridscanners of FIG. 15A, 15B or 15C.

[0069]FIG. 23 depicts an aircraft mounting arrangement using multiplehybrid scanners of FIG. 15, 15B or 15C.

[0070] FIGS. 24A-24C depict symbols conforming to conventional matrixarray and other symbologies.

[0071]FIG. 25 is-a perspective view of another embodiment of a scanner.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0072] FIGS. 1-4 of the drawings refer to the embodiment set forth inparent application U.S. Ser. No. 08/093,967, filed Jul. 21, 1993, andthe related applications set forth above under the Reference to RelatedApplications. Reference numeral 10 generally identifies a light-weight,narrow-bodied, streamlined, narrow-snouted, hand-held, fully portable,easy-to-manipulate, non-arm-and-wrist-fatiguing, twin-windowed laserscanning head supportable entirely by a user for use in an opticalscanning system operative for reading, scanning and/or analyzingoptically encoded symbols or other indicia. Such symbols may, forexample, comprise a series of lines and spaces of varying widths or anyarray of geometric shapes, which pattern decodes to a multiple-digitrepresentation characteristic of the product bearing the symbol.

[0073] The head 10 includes a generally gun-shaped housing having ahandle portion 12 and an elongated narrow-bodied barrel or body portion14. The handle portion 12 has a cross-sectional dimension and overallsize such that it can conveniently fit in the palm of a user's hand.Both the body and handle portions are constituted of a light-weight,resilient, shock-resistant, self-supporting material, such as asynthetic plastic material. The plastic housing is preferablyinjection-molded, but can be vacuum-formed or blow-molded to form a thinshell which is hollow and bounds an interior space whose volume measuresless than a value which is on the order of 50 cubic inches. The specificvalue of 50 cubic inches is not intended to be self-limiting, but hasbeen provided merely to give an approximation of the overall maximumvolume and size of the head 10. The overall volume can be less than 50cubic inches and, indeed, in some applications, the volume is on theorder of 25 cubic inches.

[0074] The body portion 14 is generally horizontally elongated along alongitudinal axis, and has a front region 16 at the front end, a raisedrear region 18 at the rear end, and an intermediate body region 20extending between the front and rear regions. The body portion 14 has atop wall 11 above which the raised rear region 18 projects, a bottomwall 13 below the top wall, a pair of opposed side walls 15, 17 spacedtransversely apart of each other by a predetermined width dimension, afront wall or nose 19, and a rear wall 21 spaced rearwardly of the frontwall.

[0075] A light source means, i.e., laser tube 22 having an anode oroutput end 28 and a cathode or non-output end 25, is mounted within thebody portion 14 lengthwise along the longitudinal axis, and is operativefor generating an incident collimated laser beam. An optic means, i.e.,an optic train, is likewise mounted within the body portion, and isoperative for directing the incident beam along a light path towards areference plane located exteriorly of the housing in the vicinity of thefront region 16, as shown in FIGS. 3 and 4. A symbol to be read islocated in the vicinity of the reference plane, that is, anywhere withinthe depth of focus of the incident beam as described below, and thelight reflected from the symbol constitutes reflected light from thelaser beam which is directed along a light path away from the referenceplane and back towards the housing.

[0076] As best shown in FIG. 1D the optic train includes an opticalbench 24, a negative or concave lens 26 which is fixedly mounted in acylindrical bore 25 of the bench, a light-reflecting mirror 26′ which isfixedly mounted on an inclined surface 29 of the bench, a positive orconvex lens 30 which is adjustably mounted on the bench by means of aset screw 31, and still another light-reflecting mirror 32 which isadjustably mounted on a bendable metal bracket 33.

[0077] The optical bench 24 has an enlarged cylindrical recess 35 whichcommunicates with the smaller bore 25. The laser tube 22 is snuglyreceived in a cylindrical support sleeve 34 which, in turn, is snuglyreceived in the bore 25. An electrically conductive element or washer 36is located at the shoulder between the recess 35 and bore 25. The washer36 makes an electromechanical, non-soldered contact with the output end23 of the tube. Another electrically conductive element, preferably aresilient wire 38, is mounted at the non-output end 25 of the tube. Thewire 38 has one coiled end looped around the non-output end 25, anintermediate taut wire portion extending lengthwise of the tube, and itsother end is fixedly secured to the bench 24 by the set screw 37. Thewire 38 is preferably made of resilient, spring-like material, and itstautness functions much like a spring or biasing means for affirmativelyurging the output end 23 into affirmative, electromechanical contactwith the washer 36. The non-output end 25 is grounded via the wire 38;and a high voltage power wire (not shown) from the power supplycomponent 40 mounted in the handle portion 12 is electrically connectedto a ballast resistor 42 mounted in another bore formed in the bench 24.The ballast resistor is, in turn, electrically connected to the washer36 by a wire, not illustrated for the sake of clarity. It will be notedthat neither the output nor non-output end of the tube is directlysoldered to any electrical wire, a feature which is highly desirable ineffecting on-site tube replacement. The bore 25 and recess 35 aremechanically bore-sighted so that the laser output beam is automaticallyoptically aligned with the optic train when the sleeve-supported tubeand output end are fully inserted into the recess 35 and bore 25,respectively.

[0078] The bench 24 is a one-piece light-weight part machined orpreferably molded by inexpensive mass-production techniques of adimensionally stable, flame-retardant material, such as Delrin(Trademark), or glass-filled Noryl (Trademark), preferably having a highdielectric breakdown (on the order of 500 volts/mil). In order to takeinto account the slight variations in beam alignment which unavoidablyresult from different tubes and from tolerance variations in the tubeitself, the bore 25, and the recess 35, the very weak negative lens 26(on the order of−24 mm) is mounted very close to the output end of thetube, and all the elements in the optical path are made large enough toallow the beam to pass unobstructedly even if the beam is not exactly oncenter. The close mounting of the weak lens 26, and the short opticalpath (about 38 mm) between lenses 26 and 30, mean that the opticaltolerances in the remainder of the beam path can still be off by about{fraction (1/2)} without sacrificing system performance. This providesthe advantage that the bench can be inexpensively mass-produced withpractical tolerances.

[0079] Thus the beam emitted from the output end 23 first passes throughthe negative lens 26 which functions to diverge the initially collimatedbeam. Then, the divergent beam impinges the mirror 26, and is thereuponreflected laterally to impinge the mirror 28, whereupon the beam isreflected upwardly to pass through the positive lens 30 which isoperative to converge the divergent beam to a generally circular spot ofapproximately an 8 mil to 10 mil diameter at the reference plane. Thespot size remains approximately constant throughout the depth of focusat either side of the reference plane. The converging beam from the lens30 impinges on the adjustable mirror 32, and is thereupon laterallyreflected to a scanning mirror 44 which forms part of the scanningmeans.

[0080] The scanning means is preferably a high-speed scanner motor 46 ofthe type shown and described in copending U.S. application Ser. No.125,768, filed Feb. 29, 1980, entitled “Portable Laser Scanning Systemand Scanning Methods,” and assigned to the same assignee as the presentapplication. The entire contents of this application, now U.S. Pat. No.4,387,297, are incorporated herein by reference and made part of thisapplication. For purposes of this patent, it is sufficient to point outthat the scanner motor 46 has an output shaft 41 on which a supportplate 43 is fixedly mounted. The scanning mirror 44 is fixedly mountedon the plate 43. The motor 46 is driven to reciprocally and repetitivelyoscillate the shaft in alternate circumferential directions over arclengths of any desired size, typically less than 360°, and at a rate ofspeed on the order of a plurality of oscillations per second. In apreferred embodiment of this invention, the scanning mirror 44 and theshaft are jointly oscillated so that the scanning mirror repetitivelysweeps the beam impinging thereon through an angular distance A or anarc length of about 25 degrees and at a rate of about 40 oscillationsper second.

[0081] Stop means, i.e., an abutment 48, is fixedly mounted on a bracket49 which is, in turn, mounted on the bench 24. The abutment 48 islocated in the path of oscillating movement of the plate 43 supportingthe scanning mirror 44, for preventing the mirror from making a complete360 rotation during shipping. The abutment never strikes the mirrorduring scanning; the abutment serves to keep the mirror properlyaligned, that is, always facing towards the front of the head.

[0082] The scanning motor 46 is mounted on the bench 24 slightly offsetfrom the longitudinal axis. Other miniature scanning elements can beutilized. For example, miniature polygons driven by motors can be used,or the various bimorph scanning oscillating elements described in U.S.Pat. No. 4,251,798 can be used, or the penta-bimorph element describedin the aforementioned co-pending application can be used, or theminiature polygon element described in co-pending U.S. patentapplication Ser. No. 133,945, filed Mar. 25, 1980, entitled “PortableStand-Alone Desk-Top Laser Scanning Workstation for Intelligent DataAcquisition Terminal and Method of Scanning,” and assigned to the sameassignee as the present application, the entire contents of which arehereby incorporated herein by reference and made part of thisdisclosure, can be used.

[0083] Although only a single scanner element is shown in the drawingsfor cyclically sweeping the laser beam across the symbol along apredetermined direction (X-axis scanning) lengthwise thereof, it will beunderstood that another scanner element may be mounted in the head forsweeping the symbol along a transverse direction (Y-axis scanning) whichis substantially orthogonal to the predetermined direction. In someapplications, multiple line 'scanning is preferred. Other alternativeconfigurations could be used to provide both x and y BX13 scanning witha single scanner element. Using x and y scanning a raster,omni-directional or other scan pattern can, as desired, be formed.

[0084] Referring again to FIGS. 1-2, the scanning mirror 44 is mountedin the light path of the incident beam at the rear region of the head,and the motor 46 is operative for cyclically sweeping the incident beamthrough an angular distance A over a field of view across the symbollocated in the vicinity of the reference planes. A laserlight-transmissive scan window 50 is mounted on the raised rear region18, behind an opening 51 formed therein in close adjacent confrontingrelationship with the scanning mirror 44 thereat. As used throughout thespecification and claims herein, the term “close adjacent confronting”relationship between components is defined to mean that one component isproximally located relative to the other component, typically less thanone inch apart of each other. As shown in FIG. 1A, the scan window 50 isconfigured and positioned in the light path of the incident beam topermit the latter coming from the scanning mirror 44 to travel adistance of less than one inch within the raised rear region 18, andthen to pass through the scan window 50, and thereupon to travelunobstructedly and exteriorly of and past the intermediate body region20 and the front region 16 of the housing, and then to impinge on thesymbol located at or near the reference plane.

[0085] The closer the scanning mirror 44 is to the scan window 50, thelarger will be the field of view of the swept incident beam for a givenscan angle. It will be noted that the width dimension of the scan windowrepresents a limiting factor for the sweep of the incident beam, becausethe housing walls bounding the scan window would clip and block any beamwhich was swept beyond the width of the scan window. Hence, as a rule,the scanning mirror is made as close as possible to the scan window tooptimize the field of view of the swept incident beam. As best shown inFIG. 2, the field of view of the swept incident beam is substantiallyindependent of the width of the body portion 14 and, in fact, the fieldof view, i.e., the transverse beam dimension, of the swept incident beamis actually larger than the width of the body portion 14 at the frontregion 16 and at the forward section of the intermediate body region 20.This is, of course, due to the fact that the swept incident beam hasbeen transmitted outside of the front and intermediate body regions ofthe housing. The side walls 15, 17 are not in the light path and do notclip or block the swept incident beam. The scan window 50 is mounted onthe rear region 18 at an elevation above the top wall 11 to permit anoverhead unobstructed transmission.

[0086] In a preferred embodiment, the width of the body portion 14 is onthe order of 1¾ inches, whereas the field of view at the reference planeis on the order of 3½ inches. In prior art wide-bodied designs, thewidth of the housing was greater than 3½ inches in order to obtain a 3½inch field of view for a given scan angle. Hence, the exteriortransmission of the swept incident beam permits the head of the presentinvention to have a narrow-bodied streamlined configurations. The sidewalls 15, 17 need no longer diverge outwardly towards the front as inprior art designs to accommodate the swept beam, but can be madesubstantially parallel as shown, or in any other desired shape.

[0087] In a preferred embodiment, the reference plane is located about 2inches from the front wall 19 of the head, and is located a lineardistance of about 9½ inches from the positive lens 30. The depth offield at the reference plane is about 2¾ on either side of the referenceplane. These numerical figures are not intended to be self-limiting, butare merely exemplary. A laser light-transmissive non-scan window 52 ismounted on the front wall 19 in close adjacent confronting relationshipwith the sensor means 54 located the front region 16. The sensor means54 is operative for detecting the intensity of the light in thereflected beam coming from the symbol over a field of view across thesame, and for generating an electrical analog signal indicative of thedetected light intensity. In order to increase the zone of coverage ofthe sensor means, a pair of sensor elements or photodiodes 54 a, 54 bare located on opposite sides of the longitudinal axis. The sensorelements lie in intersecting planes and face both forwardly andlaterally. The front wall 19 is likewise constituted of a pair oftapered wall portions 19 a, 19 b, each of which has an opening 53 a, 53b formed therein. A pair of non-scan window portions 52 a, 52 b isfixedly mounted behind the openings 52 a, 52 b, respectively. Eachnon-scan window portion is mounted in close adjacent confrontingrelationship with its respective sensor element. The non-scan windowportions are configured and positioned in the light path of thereflected beam to permit the latter to pass therethrough to the sensorelements. Two small non-scan window portions are preferably utilized,rather than a single non-scan window, because two smaller windows areinherently stronger than one due to the greater perimeter that twowindows provide.

[0088] The scan window 50 is located rearwardly of the non-scan window52. Each window 50, 52 is located at a different distance from thereference plane and the front wall 19. The scan window 50 is elevatedabove the non-scan window 52, as described above. The non-scan windowportions are located at opposite sides of the longitudinal axis. Thescan window is located on the longitudinal axis.

[0089] A printed circuit board 59 is mounted within the body portion 14,and various electrical sub-circuits diagrammatically represented byreference numerals 55, 56, 57, 58 are provided on the board 59. Signalprocessing means 55 is operative to process the analog signal generatedby the sensor elements to a digitized signal to generate therefrom datadescriptive of the symbol. Suitable signal processing means for thispurpose was described in U.S. Pat. No. 4,251,798. Sub-circuit 56constitutes drive circuitry for the scanner motor 46. Suitable motordrive circuitry for this purpose was described in the aforementionedco-pending application Ser. No. 125,768. Sub-circuits 57 and 58constitute a safety circuit for the laser tube, and voltage regulatorcircuitry. Suitable circuitry for this purpose were also described inco-pending application Ser. No. 125,768.

[0090] Shock mounting means are mounted at the front end rear regions ofthe body portion, for shock mounting the laser, optical and scanningcomponents within the body portion. An annular shock collar 60,preferably of rubber material, surrounds the forward end of the tube 22and engages the bottom wall 13 and the underside of the circuit board59. Board support elements 61 a, 61 b extend downwardly of the top wall11 to rigidly support the circuit board 59. A pair of rubber shockmounts 62 are fixedly mounted on opposite sides of the optical bench 24,and respectively engage the side walls 15, 17 at the rear region 18 ofthe housing. The shock mounts 62 and the collar 60 are spacedlongitudinally apart of each other and engage the thin-walled housing atthree spaced locations to isolate twisting of the housing from the laseroptical and scanning components.

[0091] Electrical power is supplied to the laser tube 22 by the powersupply component 40 mounted within the handle portion 12. The powersupply component which steps up from a 12 volt DC battery voltage toover 1 kilovolt is the heaviest component in the head, and its mountingin the handle portion allows for a low center of gravity and for betterbalance of the head.

[0092] A non-bully, collapsible, coil-type cable 66 as shown in FIG. 2,electrically connects the head 10 to the remainder of the scanningsystem, which includes a battery-powered decode module 68 and a hostcomputer 70. The coil-type cable 66 is readily flexible and permits usermanipulation of the head 10 with multiple freedoms of movement from onesymbol to the next without requiring excessive strength by the user. Thecable 66 includes a plurality of conductive wires which are allrelatively thin and flexible. For example, one wire carries the 12 voltDC low voltage signal from the battery in the decode nodule 68 to thepower component 40. Another wire carries the digitized signal from theanalog-to-digital signal processing circuitry 55 to the decode module 68for decoding purposes. This latter wire is non-radio-frequency-shielded,and hence, is readily flexible. The remaining wires carry low voltagecontrol and communication signals. All of the wires of the cable 66 areconnected together to a common plug-type connector 72. A matingconnector 74 is mounted within the head, receives the connector 72 in amating relationship. The use of the mating connectors 72, 74 permitsrapid replacement of the cable for on-site repairs. The electricalconnections between the connector 74 and the various components in thehead have been omitted from the drawings for the sake of clarity.

[0093] The decode module 68 processes the digitized signal generated inthe head, and calculates the desired data, e.g. the multiple digitrepresentation or code of the symbol, in accordance with an algorithmcontained in a software program. The decode module 68 includes a PROMfor holding the control program, a RAM for temporary data storage, and amicroprocessor which controls the PROM and RAM and does the desiredcalculations. The decode module also includes control circuitry forcontrolling the actuatable components in the head as described below, aswell as two-way communications circuitry for communicating with the headand/or with the host computer 70. The host computer 70 is essentially alarge data base, and provides information relating to the decodedsymbol. For example, the host computer can provide retail priceinformation corresponding to the decoded symbols.

[0094] A manually-actuatable trigger switch 76 is mounted on the head inthe region where the handle portion 12 is joined to the body portion 14.Depression of the trigger switch 76 is operative to turn themicroprocessor in the decode module on. Upon release of the triggerswitch, the spring 78 restores the switch to its initial position, andthe microprocessor is turned off. In turn, the microprocessor iselectrically connected to the actuatable components in the head via thecable 66 to actuate and deactuate the actuatable components when themicroprocessor is respectively turned on or off by the trigger switch.

[0095] In prior art heads, the trigger switch was only operative to turnthe laser tube and/or scanner motor on or off. Now, the trigger switchturns the microprocessor on or off and, in turn, all of the actuatablecomponents in the head on or off. The microprocessor is a large powerdrain on the battery built into the decode module. Hence, by controllingthe on-time of the microprocessor to only those times when a symbol isbeing read, that is, when the trigger switch is depressed, the powerdrain is substantially reduced, and the battery life substantiallyincreased (over 5 hours).

[0096] Another feature of this invention is embodied in turning themicroprocessor on or off by means of the host computer 70 which isremote from the head 10. The computer 70 typically includes a keyboardand a display. Once a user makes an entry on the keyboard, for example,by entering the identity of the code to be decoded, the computerrequests the microprocessor to turn itself on, store the information,and then to turn itself off. The microprocessor, again, is on only forso long as is necessary to comply with the computer request. The triggerswitch and the keyboard computer entry are independently operable meansfor directly controlling the microprocessor, and for indirectlycontrolling the actuatable components in the head.

[0097] Another useful feature in having the microprocessor, rather thanthe trigger switch, directly control the laser tube is to keep anaccurate record of laser on-time for governmental record keeping. It is,of course, far easier to keep track of laser on-time in the software ofa microprocessor than to manually record the laser on-time. Using themicroprocessor, the laser tube might be activated only after asatisfactory read of one symbol and until another symbol is properlyread. Alternatively, the laser tube could remain activated until apredetermined period of time passes without a decode.

[0098] A set of visual indicators or lamps 80, 82, 84 is also mounted onthe circuit board 59, each lamp being positioned below a correspondingopening in the top wall 11. The lamps are operative to visually indicateto the user the status of the scanning system. For example, lamp 80illuminates whenever the laser tube is energized, thereby continuouslyadvising the user whether the tube is on or off. Lamp 82 illuminateswhen a successful decode has been obtained. It will be recalled that theincident beam is swept over a symbol at a rate of about 40 scans persecond. The reflected beam may be successfully decoded on the firstscan, or on any of the successive scans. Whenever a successful scan hasbeen obtained, the microprocessor will cause the lamp 84 to beilluminated to advise the user that the head is ready to read anothersymbol.

[0099] It is believed that the operation of the scanning system isself-evident from the foregoing, but by way of brief review, thegun-shaped head is grasped by its handle portion, and its barrel isaimed at the symbol to be read. The sighting of the symbol isfacilitated by the fact that the barrel is narrow-bodied, and that thereare no obstructions on the front and intermediate body regions of thebarrel. The front wall of the barrel is situated close to the symbol, itbeing understood that the symbol can be located anywhere in the depth offield at either side of the reference plane.

[0100] The trigger switch is then depressed, thereby causing themicroprocessor to energize the laser tube, the scanner motor, the sensorelements, and all the electronic circuitry provided on the printedcircuit board. The laser tube emits a beam, which is then routed throughthe optic train as described above, and thereupon, the scanning mirrorreflects the beam through the scan window and out of the head exteriorlyof and past the front and intermediate body regions of the body portionof the head. The reflected beam light passes through the non-scan windowportions to the sensor elements and is subsequently processed by thesignal processing circuitry. The processed signal is conducted to thedecode module for decoding. Once a successful decode has been realized,the microprocessor illuminates the lamp 82 and if desired may deactuatethe head, and the user is now advised by illumination by lamp 84 thatthe head is ready to be aimed at another symbol. The flexibility of thecoil-type cable facilitates the movement of the head to the next symbol.

[0101] In addition, the movement of the head from one symbol to the nextis facilitated by the relatively low weight of the head. The head withall the aforementioned components therein weighs less than one pound.This represents a significant breakthrough in the art of miniaturizedand portable laser scanning heads.

[0102] Referring now to FIGS. 3 and 4, reference numeral 130 generallyidentifies a gun-shaped, laserless, twin-windowed head analogous to theprevious heads 10, 100, except as noted below. To simplify thedescription of head 130, like parts previously described in connectionwith the earlier embodiment have been identified with like referencenumerals. One major distinction of the head 130 is that the incidentbeam is not swept, but is transmitted from the front of the housing, andthat it is the reflected beam that is preferably swept over its field ofview. Put another way, the sensor means preferably a linear array ofcharge coupled devices or a two-dimensional array of solid state imagingdevices sweeps across the symbol. It will be understood, however, thatif desired the sensor could be provided with the capability to operatein either or both scanning and non-scanning modes with the appropriateoperation being selectable to the suitability for the particularfunction, e.g. reading, ambient light detection, range finding, to whichthe sensor is directed. When operating in a scanning mode, the sensormay scan the field of view at a rate which can be faster orsubstantially slower than the scanning light beam scan. The sensor maybe controlled to scan the field of view periodically. It is thereflected beam that unobstructedly travels exteriorly of and past thefront and intermediate body regions of the housing.

[0103] Rather than a laser tube or laser diode, the laserless head 130comprises a light source 132 which includes a pair of light sourceelements 132 a, 132 b at opposite sides of the longitudinal axis, eachlight source element facing both forwardly, upwardly and laterally toemit a light beam. Again, the light source elements need not generate alaser beam but are operative to generate any type of light beam, and mayconstitute high-powered LED's (30-100 mW) or a miniature quartz halogenbulb. The incident light beam passes through a light transmissive frontnon-scan window 152 located at the front region 16 of the body portion20 of the head in close adjacent confronting relationship with the lightsource elements 132 a, 132 b thereat. In a variant from non-scan window52, the non-scan window 152 is a wraparound window which extendstransversely along the front and also partially along the side walls ofthe head. After passing through the non-scan window 152, the incidentbeam illuminates the symbol. It is preferable if the incident beam isdirected slightly upwardly, such that the reflected beam will bedirected, as shown, that is, exteriorly of and past the front region 16and intermediate body region 20 above the top wall of the body portionThe reflected beam passes through the raised rear scan window 150 andimpinges on the scanning mirror 44 which is being repetitivelyoscillated by the scanner motor 46 to scan the field of view of thereflected beam across the symbol. The swept reflected beam is thereupondirected towards the light-reflecting mirror 134 which is adjustablymounted on a bendable mounting bracket 136 on a sensor optic tube 138.The mirror 134 is positioned in the light path of the reflected beam todirect the reflected light off the mirror 44 through the sensor opticstube 138 to the sensor means 140 mounted within the body portion 14 atthe rear region 18 of the head.

[0104] As best shown in FIG. 4, the reflected light beam is swept over atransverse beam dimension which is larger the width of the body portion.Hence, here again, the field of view of the swept reflected beam issubstantially independent of the barrel width.

[0105] FIGS. 5-7 of the drawings refer to the embodiment set forth inparent application U.S. patent Ser. No. 08/074,641, filed Jun. 11, 1993and the related applications set forth above under the Reference toRelated Applications. Reference numeral 910 generally identifies alightweight (less than one pound), narrow-bodied, streamlined,narrow-snouted, hand-held, fully portable, easy-to-manipulate,non-arm-and-wrist fatiguing laser scanning system operative for reading,scanning and/or analyzing symbols, and amiable both prior to, andduring, the reading thereof, by the user at the symbols, each symbol inits turn.

[0106] The head 910 includes a generally gun-shaped housing having ahandle portion 912 of generally rectangular cross-section and generallyvertically elongated along a handle axis, and a generally horizontallyelongated, narrow-bodied barrel or body portion 914, The cross-sectionaldimension and overall size of the handle portion 912 is such thatconveniently can fit and be held in a user's hand. The body and handleportions are constituted of a lightweight, resilient, shock-resistant,self-supporting material, such as a synthetic plastic material. Theplastic housing preferably is injection-molded, but can be vacuum-formedor blow-molded to form a thin, hollow shell which bounds an interiorspace whose volume measures less than a value on the order of 50 cubicinches and, in some applications, the volume is on the order of 25 cubicinches or less. Such specific values are not intended to beself-limiting, but to provide a general approximation of the overallmaximum size and volume of the head 910.

[0107] As considered in an intended position of use as shown in FIGS.5-7, the body portion 914 has a front prow region having an upper frontwall 916 and a lower front wall 918 which forwardly converge toward eachother and meet at a nose portion 920 which lies at the foremost part ofthe head. The body portion 914 also has a rear region having a rear wall922 spaced rearwardly of the front walls 916, 918. The body portion 914also has a top wall 924, a bottom wall 926 below the top wall 924, and apair of opposed side walls 928, 930 that lie in mutual parallelismbetween the top and bottom walls.

[0108] A manually-actable, and preferably depressive, trigger 932 ismounted for pivoting movement about a pivot axis 934 on the head in aforwardly-facing region where the handle and body portions meet andwhere the user's forefinger normally lies when the user grips the handleportion in the intended position of use. The bottom wall 926 has atubular neck portion 936 which extends downwardly along the handle axis,and terminates in a radially-inwardly extending collar portion 938generally rectangular cross-section. The neck and collar portions have aforwardly-facing slot through which the trigger 932 projects and ismoved.

[0109] The handle portion 912 has a radially-outwardly extending upperflange portion 940 of generally rectangular cross-section which also hasa forwardly-facing slot through which the trigger 32 projects and ismoved. The upper flange portion 940 is resilient and deflectable in aradially-inward direction. When the upper flange portion 940 is insertedinto the neck portion 936, the upper flange portion 940 bears againstthe collar portion 938 and is radially-inwardly deflected until theflange portion 940 clears the collar portion 938, at which, the upperflange portion 940, due to its inherent resilience, snaps back to itsinitial undeflected position and engages behind the collar portion witha snap-type looking action. To disengage the handle portion from thebody portion, the upper part of the handle portion is sufficientlydeflected until the upper flange portion 940 again clears the collarportion, and thereupon the handle portion can be withdrawn from the neckportion 936. In this manner, handle portion 912 can be detachablysnap-mounted and de-mounted from the body portion 914 and, as explainedbelow, another handle portion from a set of interchangeable handleportions, each containing different components of the laser scanningsystem, may be mounted to the body portion to adapt the head 910 todifferent user requirements.

[0110] A plurality of components are mounted in the head and, asexplained below, at least some of them are actuated by the trigger 932,either directly or indirectly, by means of a control microprocessor. Oneof the head components is an actuable laser light source, e.g. asemiconductor laser diode 942 operative, when actuated by the trigger932, for propagating and generating an incident laser beam whose light,as explained above, is “invisible” or non-readily visible to the user,is highly divergent, is non-radially symmetrical, is generally oval incross-section, and has a wavelength above 7000, e.g. about 7800 mAngstrom units. Advantageously, the diode 942 is commercially availablefrom many sources, e.g. from the Sharp Corporation as its Model No.LT020MC. The diode may be of the continuous wave or pulse type. Thediode 942 requires a low voltage, e.g. 12 v DC or less, supplied by abattery (DC) source which may be provided within the head, or by arechargeable battery pack accessory detachably mounted on the head, orby a power conductor in a cable 946, see FIG. 5 connected to the headfrom an external power supply, e.g. DC source.

[0111] The aperture stop 956 is positioned in the center of the laserdiode beam so that the intensity of light is approximately uniform inthe planes both perpendicular and parallel to the p-n junction, i.e. theemitter, of the diode 942. It will be noted that, due to the non-radialsymmetry of the laser diode beam, the light intensity in the planeperpendicular to the p-n junction is brightest in the center of the beamand then falls off in the radially outward direction. The same is truein the plane parallel to the p-n junction, but the intensity falls offat a different rate. Hence, by positioning a preferably circular, smallaperture in the center of a laser diode beam having an oval, largercross-section, the oval beam cross-section at the aperture will bemodified to one that is generally circular, and the light intensity inboth of the planes perpendicular and parallel to the p-n junctionapproximately is constant. The aperture stop preferably reduces thenumerical aperture of the optical assembly to below 0.05, and permitsthe single lens 958 to focus the laser beam at the reference plane.

[0112] In a preferred embodiment, the approximate distance between theemitter of the laser diode 942 and the aperture stop 956 ranges fromabout 9.7 mm. The focal distance of the lens 958 ranges from about 9.5mm to about 9.7 mm. If the aperture stop 956 is circular, then itsdiameter is about 1.2 mm. It the aperture stop 956 is rectangular, thenits dimensions are about 1 mm by about 2 mm. The beam cross-section isabout 3.0 mm by about 9.3 mm just before the beam passes through theaperture stop 956. These merely exemplary distances and sizes enable theoptical assembly to modify the laser diode.

[0113] As best shown in FIG. 8, a representative symbol 9100 in thevicinity of the reference plane is shown and, in the case of a bar codesymbol, is comprised of a series of vertical bars spaced apart of oneanother along a longitudinal direction. The reference numeral 9106denotes the generally circular, invisible, laser spot subtended by thesymbol. The laser spot 9106 in FIG. 8 is shown in an instantaneousposition, since the scanning mirror 966, when actuated by the trigger32, is, as explained below, reciprocally and repetitively oscillatedtransversely to sweep the incident laser beam lengthwise across all thebars of the symbol in a linear scan. The laser spots 9106 a and 9106 bin FIG. 8 denote the instantaneous end positions of the linear scan. Thelinear scan can be located anywhere along the height of the barsprovided that all the bars are swept. The length of the linear scan islonger than the length of the longest symbol expected to be read and, ina preferred case, the linear scan is on the order of 5 inches at thereference plane.

[0114] The scanning mirror 966 is mounted on a scanning means,preferably a high-speed scanner motor 970 of the type shown anddescribed in U.S. Pat. No. 4,387,397, the entire contents of said patentbeing incorporated herein by reference and made part of the instantapplication. For the purposes of this application, it is believed to besufficient to point out that the scanner motor 970 has an output shaft972 on which a support bracket 974 is fixedly mounted. The scanningmirror 966 is fixedly mounted on the bracket 974. The motor 970 isdriven to reciprocally and repetitively oscillate the shaft 972 inalternate circumferential directions over arc lengths of any desiredsize, typically less than 360 degrees, and at a rate of speed on theorder of a plurality of oscillations per second. In a preferredembodiment, the scanning mirror 966 and the shaft 972 jointly areoscillated so that the scanning mirror 966 repetitively sweeps theincident laser diode beam impinging thereon through an angular distanceor arc length at the reference plane of about 32 degrees and at a rateof about 40 scans or 20 oscillations per second.

[0115] Referring again to FIG. 6, the returning portion of the reflectedlaser light has a variable light intensity, due to the differentlight-reflective properties of the various parts that comprise thesymbol 9100, over the symbol during the scan. The returning portion ofthe reflected laser light is collected by a generally concave, sphericalcollecting mirror 976, and is a broad conical stream of light in aconical collecting volume bounded, as shown in FIG. 6, by upper andlower boundary lines 9108, 9110, and, as shown in FIG. 7, by opposedsize boundary lines 9112, 9114. The collecting mirror 976 reflects thecollected conical light into the head along an optical axis 9116 asshown in FIG. 7, along the second optical path through alaser-light-transmissive element 978 to a sensor means, e.g. aphotosensor 980. The collected conical laser light directed to thephotosensor 980 is bounded by upper and lower boundary lines 9118, 9120as shown in FIG. 6 and by opposed side boundary lines 9122, 9124, asshown FIG. 7. The photosensor 980, preferably a linear charge coupled ortwo-dimensional solid state imaging device or could have a photodiode,detects by sensing or imaging the variable intensity of the collectedlaser light over a field of view which extends along, and preferablybeyond, the linear scan, and generates an electrical analog signalindicative of the detected variable light intensity. The linear chargecoupled device is arranged within the scanner housing so that the longdimension of the charge coupled device will be parallel to the scanninglight beam.

[0116] Referring again to FIG. 8, the reference numeral 9126 denotes aninstantaneous collection zone subtended by the symbol 9100 and fromwhich the instantaneous laser spot 9106 reflects. Put another way, thephotosensor 980 “sees” the collection zone 9126 when the laser spot 9106impinges the symbol. The collecting mirror 976 is mounted on the supportbracket 974 and, when the scanner motor 970 is actuated by the trigger932, the collecting mirror 976 is reciprocally and repetitivelyoscillated transversely, sweeping the field of view of the photodiodelengthwise across the symbol in a linear scan. The collection zones 9126a, 9126 b denote the instantaneous end positions of the linear scan ofthe field of view.

[0117] The scanning mirror 966 and the collecting mirror 976 are, in apreferred embodiment, of one-piece construction and, as shown in FIG. 7,are light-reflecting layers or coatings applied to a pleno-convex lensconstituted of a light-transmissive material, preferably glass. The lenshas a first outer substantially planar surface on a portion of which afirst light-reflecting layer is coated to constitute the planar scanningmirror 966, and a second outer generally spherical surface on which asecond light-reflecting layer is coated to constitute the concavecollecting mirror 976 as a so-called “second surface spherical mirror.”

[0118] The scanning mirror 966 can also be a discrete, small planarmirror attached by glue, or molded in place, at the correct position andangle on a discrete, front surfaced, silvered concave mirror. Asdescribed below, the concave collecting mirror 976 serves not only tocollect the returning portion of the laser light and to focus the sameon the photodiode 980, but also to focus and direct an aiming light beamexteriorly of the head.

[0119] Also mounted in the head is a pair or more of printed circuitboards 984, 986 on which various electrical subcircuits are mounted. Forexample, signal processing means having components 983 and 985 on board984 are operative for processing the analog electrical signal generatedby the sensor 980, and for generating a digitized video signal. Datadescriptive of the symbol can be derived from the video signal. Suitablesignal processing means for this purpose was described in U.S. Pat. No.4,251,798. Components 987 and 989 on board 986 constitute drivecircuitry for the scanner motor 970, and suitable motor drive circuitryfor this purpose was described in U.S. Pat. No. 4,387,297. Component 991on board 986 constitutes an aiming light controller subcircuit whoseoperation is described below. Component 993 on board 948, on which thediode 942 and sensor 980 are mounted, is a voltage converter forconverting the incoming voltage to one suitable for energizing the laserdiode 942. The entire contents of U.S. Pat. Nos. 4,251,798 and 4,387,297are incorporated herein by reference and made part of the instantapplication.

[0120] The digitized video signal is conducted to an electricalinterlock composed of a socket 988 provided on the body portion 914, anda mating plug 990 provided on the handle portion 912. The plug 990automatically electromechanically mates with the socket 988 when thehandle portion is mounted to the body portion. Also mounted within thehandle portion are a pair of circuit boards 992, 994, as shown FIG. 5 onwhich various components are mounted. For example, a decode/controlmeans comprised of components 995, 997 and others are operative fordecoding the digitized video signal to a digitized decoded signal fromwhich the desired data descriptive of the symbol is obtained, inaccordance with an algorithm contained in a software control program.The decode/control means includes a PROM for holding the controlprogram, a Roll for temporary data storage, and a control microprocessorfor controlling the PROM and RAM. The decode/control means determineswhen a successful decoding of the symbol has been obtained, and alsoterminates the reading of the symbol upon the determination of thesuccessful decoding thereof. The initiation of the reading is caused bydepression of the trigger 932. The decode/control means also includescontrol circuitry for controlling the actuation of the actuatablecomponents in the head, as initiated by the trigger, as well as forcommunicating with the user that the reading has been automaticallydetermined as, for example, by sending a control signal to an indicatorlamp 996 to illuminate the same.

[0121] The decoded signal is conducted, in one embodiment, along asignal conductor in the cable 946 to a remote, host computer 9128 whichserves essentially as a large data base, stores the decoded signal and,in some cases, provides information related to the decoded signal. Forexample, the host computer can provide retail price informationcorresponding to the objects identified by their decoded symbols.

[0122] In another embodiment, a local data storage means, e.g. component995, is mounted in the handle portion, and stores multiple decodedsignals which have been read. The stored decoded signals thereupon canbe unloaded to a remote host computer. By providing the local datastorage means, the use of the cable 946 during the reading of thesymbols can be eliminated—a feature which is very desirable in makingthe head as freely manipulatable as possible.

[0123] As noted previously, the handle portion 912 may be one of a setof handles which may be interchangeably mounted to the body portion. Inone embodiment, the handle portion may be left vacant, in which case,the video signal is conducted along the cable 946 for decoding in aremote decode/control means. In another embodiment, only thedecode/control means may be contained within the handle portion, inwhich case, the decoded signal is conducted along the cable 946 forstorage in a remote host computer. In still another embodiment, thedecode/control means and a local data storage means may be containedwithin the handle portion, in which case, the stored decoded signalsfrom a plurality of readings thereupon may be unloaded in a remote hostcomputer, the cable 946 only being connected to unload the storedsignal.

[0124] Alternatively, rather than providing a set of removable handles,a single handle can be non-detachably fixed to the head and, in thisevent, different components mounted on removable circuit boards 992 and994 may be provided, as desired, within the single handle by removing,and thereupon replacing, the removable handle end 9128.

[0125] As for electrically powering the laser diode 942, as well as thevarious components in the head requiring electrical power, a voltagesignal may be conveyed along a power conductor in the cable 946, and aconverter, such as component 993, may be employed to convert theincoming voltage signal to whatever voltage values are required. Inthose embodiments in which the cable 946 was eliminated during thereading of the symbols, a rechargeable battery pack assembly isdetachably snap-mounted at the bottom of the handle portion 912.

[0126] In further accordance with this invention and as shown in FIG. 9,an aiming light arrangement is mounted within the head for assisting theuser in visually locating, and in aiming the head at, each symbol to beread in its turn, particularly in the situation described above whereinthe laser beam incident on, and reflected from, the symbol is notreadily visible to the user. The aiming light arrangement comprisesmeans including an actuatable aiming light source 9130, e.g. a visiblelight-emitting diode (LED), an incandescent white light source, a xenonflash tube, etc., mounted in the head and operatively connected to thetrigger 932. When actuated either directly by the trigger 932 orindirectly by the decode/control means, the aiming light 9130 propagatesand generates a divergent aiming light beam whose light is readilyvisible to the user, and whose wavelength is about 6600 Angstrom units,so that the aiming light beam generally is red in color and thuscontrasts with the ambient white light of the environment in which thesymbol is located.

[0127] Aiming means also are mounted in the head for directing theaiming light beam along an aiming light path from the aiming lightsource toward the reference plane and to each symbol, visiblyilluminating at least a part of the respective symbol. Morespecifically, as shown in FIG. 7, the aiming light 9130 is mounted on aninclined support 9132 for directing the generally conical aiming lightbeam at the optical element 978. The conical aiming light beam isbounded by upper and lower boundary lines and by opposed side boundarylines in route to the optical element 978. As previously noted, theoptical element 978 permits the collected laser light to passtherethrough to the photosensor 980, and filters out ambient light noisefrom the environment from reaching the photosensor. The optical element978 also reflects the aiming light beam impinging thereon. The opticalelement is, in effect, a so-called “cold” mirror which reflects light inwavelengths in the range of the aiming light beam, but transmits lightin wavelengths in the range of the laser light. The aiming light beam isreflected from the cold mirror 978 along an optical axis which issubstantially collinear with the optical axis 9116 of the collectedlaser light between the collecting mirror 976 and the photosensor 980,and impinges on the concave mirror 976 which serves to focus andforwardly reflect the aiming light beam along an optical axis which issubstantially collinear with the same optical axis of the collectedlaser light between the concave mirror 976 and the symbol 9100. Theconcave mirror 976 which serves as a focusing mirror for the aiminglight beam focuses the same to about a one-half inch circular spot sizeat a distance about 8 inches to about 10 inches from the nose 20 of thehead. It will be noted that the portion of the aiming light path whichlies exteriorly of the head coincides with the portion of the collectedlaser light path which lies exteriorly of the head so that thephotosensor 980, in effect, “sees” the non-readily-visible laser lightreflected from that part of the symbol that has been illuminated, orrendered visible, by the aiming light beam. In another variant, theaiming light beam could have been directed to the symbol so as to becoincident with the outgoing incident laser beam by placing a coldmirror in the first optical path and directing the aiming light beam atthe cold mirror so that the optical axis of the aiming light beam iscoincident with that of the outgoing incident laser beam.

[0128] As shown in FIG. 9, the aiming LED 9130 may, in a first staticsingle beam aiming embodiment, be positioned relative to a stationarydirecting element 9142, e.g. a focusing lens, stationarily mounted inthe aiming light path within the head. The lens 9142 is operative forfocusing and directing the aiming light beam to the respective symbol9100, visibly illuminating thereon a spot region 9150, see also FIG. 10,within the field of view. The spot region 9150 preferably is circular,near the center of the symbol, and is illuminated both prior to the scanto locate the symbol before the reading thereof, and during the scan andthe reading thereof. Both close-in and far-out symbols can be locatedand: seen by the static single beam aiming embodiment of FIG. 9, thefar-out symbols, due to their greater distance from the head, beingilluminated to a lesser intensity, but visible, nevertheless, by theuser. However, as explained previously, the fixed spot 9150 provideslittle assistance in terms of tracking the scan across the symbol.

[0129] Turning next to a second static twin beam aiming embodiment, asshown in FIG. 11, a pair of aiming LEDs 9130 a, 9130 b, each identicalto aiming LED 9130, are angularly positioned relative to the stationaryfocusing lens 9142 which, in turn, is operative to direct the aiminglight beams of both LEDs 9130 a, 9130 b to the same respective symbol,visibly illuminating thereon a pair of spot regions 9152 and 9154 thatare within, and spaced linearly apart of each other along the field ofview, see also FIG. 10. The spot regions 9152 and 9154 preferably arecircular, near the ends of the scan and are illuminated both prior toand during the scan to locate and track the respective symbol bothbefore and during the reading thereof. Both close-in and far-out symbolscan be located and seen by the static twin beam aiming embodiment ofFIG. 11, the far-out symbols, due to their greater distance from thehead, being illuminated to a lesser intensity, but visible,nevertheless, by the user. As explained previously, the pair of fixedspots 9152 and 9154 provide valuable assistance in terms of tracking thescan across the symbol.

[0130] Turning next to a third dynamic single beam aiming embodiment,and with the aid of FIG. 10, rather than stationarily mounting thefocusing lens 9142 in the head, the lens 9142 may be oscillated in themanner described previously for the scanning/collecting/focusingcomponent to sweep the aiming light beam across the respective symbol,illuminating thereon a line region 9156; see FIG. 12, extending alongthe field of view. The line region 9156 is illuminated during the scanto track the respective symbol during the reading thereof. Close-insymbols are well illuminated by the line region 9156, even when the scanis performed at rates of 40 scans per second; however, for far-outsymbols, the greater the distance from the head and the faster the scanrage, the less visible is the line region 9156.

[0131] Returning to FIGS. 5-7, a combination static/dynamic aimingarrangement is shown which is actuated by the trigger 32 among variouspositions or states. In FIG. 6, the trigger 32 is shown in an off state,wherein all the actuatable components in the head are deactivated. Apair of electrical switches 9158 and 9160 are mounted on the undersideof board 984. Each switch 9158, 9160 has a spring-biased armature orbutton 9162, 9164 which, in the off state, extend out of the switchesand bear against opposite end regions of a lever 9166 which is pivotedat a center-offset position at pivot point 9168 on a rear extension 9170of the trigger 932.

[0132] When the trigger 932 is initially depressed to a first initialextent, the lever 9166 depresses only the button 9162, and the depressedswitch 9158 establishes a first operational state in which the trigger932 actuates the aiming light 9130 as shown in FIG. 7 only, whose aiminglight beam is thereupon reflected rearwardly off cold mirror 978 andreflected forwardly off the focusing mirror 976 to the symbol. In saidfirst operational state, the trigger has also positioned the focusingmirror 976 in a predetermined stationary position. The stationaryfocusing mirror 976 directs the aiming light beam to the symbol, visiblyilluminating thereon a soot region, identical to central spot region9150 in FIG. 10 within the field of view prior to the scan to assist theuser in locating the symbol before the reading thereof. The stationarypositioning of the focusing mirror 976 is advantageously accomplished byenergizing a DC winding of the scanning motor 970 so that the outputshaft and the focusing mirror 976 mounted thereon are angularly turnedto a central reference position.

[0133] Thereupon, when the trigger 932 is depressed to a second furtherextent, the lever 9166 depresses not only the button 9162, but also thebutton 9164, so that a second operational state is established. In saidsecond operational state, the trigger actuates all the remainingactuatable components in the head, e.g. the laser diode 942, the controlcircuitry of the scanner motor 970 which causes the focusing mirror 976to oscillate, and the photodiode 980, the signal processing circuitry,as well as the other circuitry in the head, to initiate a reading of thesymbol. The focusing mirror 976 no longer is stationary, but is beingoscillated so that the aiming light beam dynamically is swept across thesymbol, visibly illuminating thereon a line region, identical to lineregion 9156 in FIG. 12, extending along the field of view. Hence, duringthe scan, the user is assisted in tracking the symbol during the readingthereof. Such symbol tracking is highly visible for close-in symbols,but less so for far-out symbols.

[0134] The aforementioned sequential actuation of the components in thehead could also be done with a single two-pole switch having built-insequential contacts.

[0135] The laser scanning head of FIG. 6 is of the retro-reflective typewherein the outgoing incident laser beam, as well as the field of viewof the sensor means, are scanned. It will be readily understood thatother variants also are within the spirit of this invention. For examplethe outgoing incident laser beam can be directed to, and swept across,the symbol through one window on the head, while the field of view isnot scanned and the returning laser light is collected through anotherwindow on the head. Also, the outgoing incident beam can be directed to,but not swept across, the symbol, while the field of view is scanned.

[0136] A variety of housing styles and shapes dictated by suchconsiderations as aesthetics, environment, size, choice and placement ofelectronic and mechanical components, required shock resistance bothinside and outside the housing, may be employed in place of the housingshown in the drawings.

[0137] The laser scanning head of this invention need not be handheld,but can also be incorporated in a desk-top, stand-alone workstation,preferably underneath an overhead window or port through which theoutgoing incident laser beam is directed. Although the workstationitself is stationary, at least during the scanning of the symbol, thesymbol is movable relative to the workstation and must be registeredwith the outgoing beam and, for this purpose, the aiming lightarrangement described herein is particularly advantageous.

[0138] It should be noted that the laser scanning head of this inventioncan read high-, and medium- and low-density bar code or other symbolswithin approximate working distance ranges of 1″ to 6″, 1″ to 12″, and1″ to 20″ respectively. As defined herein, the high-, medium- andlow-density bar code symbols would have bars and/or spaces whosesmallest width is on the order of 7.5 mils, 15-20 mils and 30-40 mils,respectively. In the preferred embodiment, the position of the referenceplane for a symbol of known density is optimized for the maximum workingdistance for that symbol.

[0139] To assist the user in aiming the head at the symbol, in additionto the aiming light arrangements described herein, other means may beprovided. For example, a mechanical aiming means such as a raisedsighting element formed on an upper portion of the housing and extendingalong the direction of the first or second optical path may be sightedalong by the user. A viewpoint having a sight window may also be locatedon the head to enable the user to look through the sight window andthereby visually locate the symbol in the window. A sonic ranging meanscan also be used for finding the symbol. The ranging means emits a sonicsignal, detects a returning echo signal, and actuates an auditoryindicator upon such detection. The auditory indicator can sound a toneor change the rate of a series of sounds or beeps, thereby signaling theuser that the symbol has been found.

[0140] In another aspect of this invention, it is sometimes desirable tocause the aforementioned aiming light spots on the symbol to blink, e.g.for the purpose of making the spots easier to see, or to reduce theaverage power consumed by the aiming light sources. Such blinking lightspots can be effected by electrical and/or mechanical means.

[0141] The present invention also provides a method and apparatus foroperating an indicia reading system in which two different types ofsymbols may be read—e.g., a standard linear bar code symbol, and atwo-dimensional bar code. The present invention also provides atechnique for selecting whether a laser scanner using a light beam toscan a symbol, or CCD imaging and scanning a field of view, is utilized.

[0142] Referring to FIG. 13, there is shown a highly simplified blockdiagram representation of an embodiment of one type of indicia readerthat may be designed according to the principles of the presentinvention. The reader 200 may be implemented in a portable scanner, oras a desk-top workstation or stationary scanner. In the Preferredembodiment, the reader is implemented in a light-weight plastic housing201.

[0143] In one preferred embodiment, the reader 200 may be a gun-shapeddevice, having a pistol-grip type of handle; another embodiment is ahand-mounted unit. A movable trigger switch (shown in FIGS. 1 and 6 onthe housing may be employed to allow the user to manually activate thescanner when the user has positioned the device to point at the symbolto be read. Various “triggerless” activation techniques can also be usedas will be subsequently described.

[0144] The first preferred embodiment may generally be of the styledisclosed in U.S. Pat. No. 4,760,248, issued to Swartz et al., or inU.S. Pat. No. 4,896,026 assigned to Symbol Technologies, Inc., and alsosimilar to the configuration of a bar code reader commercially availableas part number LS 8100 or LS 2000 from Symbol Technologies, Inc.Alternatively, or in addition, features of U.S. Pat. No. 4,387,297issued to Swartz et al., or U.S. Pat. No. 4,409,470 issued to Shepard etal., both such patents being assigned to Symbol Technologies, Inc., maybe employed in constructing the bar code reader unit of FIG. 13. TheseU.S. Pat. Nos. 4,760,248, 4,896,026 and 4,409,470, are incorporatedherein by reference, but the general design of such devices will bebriefly described here for reference.

[0145] Turning to FIG. 13 in more detail, an outgoing light beam 203 isgenerated in the reader 200 by a light source 207, usually a laser diodeor the like. The light beam from light source 207 is optically modifiedby an optical assembly 208 to form a beam having certaincharacteristics. The beam sized and shaped by the assembly 208 isapplied to a scanning unit 209. The light beam is deflected by thescanning unit 209 in a specific scanning pattern, i.e. to form a singleline, a linear raster scan pattern, or more complex pattern. The scannedbeam 203 is then directed by the scanning unit 209 through an exitwindow 202 to impinge upon a bar code or other symbol 204 disposed on atarget a few inches from the front of the reader. In the embodiments inwhich the reader 200 is portable, the user aims or positions theportable unit so this scan pattern transverses the symbol 204 to beread. Reflected and/or scattered light 205 from the symbol is detectedby a light detector 206 in the reader, producing electrical signals tobe processed and decoded for reproducing the data represented by thesymbol. As used hereinafter, the term “reflected light” shall meanreflected and/or scattered light.

[0146] The characteristics of each of the optical components 207, 208and 209 may be independently controlled by drive units 210, 211 and 212respectively. The drive units are operated by digital control signalssent over the control bus 226 by the central processing unit 219, whichis preferably implemented by means of a microprocessor contained in thehousing 201.

[0147] A second, optional light source 240, such as an LED array, mayalso be provided and independently controlled by drive unit 210.

[0148] The output of the light detector 206 is applied to an analogamplifier 213 having an adjustable or selectable gain and bandwidth. Anamplifier control unit 214 is connected to the analog amplifier 213 toeffect the appropriate adjustment of circuit values in the analogamplifier 213 in response to control signals applied to the control unit214 over the control bus 226. An ambient light sensor 241 is alsoprovided which provides an output to the control bus 226.

[0149] One output of the analog amplifier 213 is applied to ananalog-to-digital (A/D) converter 215 which samples the analog signal tobe tested by the CPU 219. The A/D converter is connected to the controlbus 226 to transfer the sampled digital signal for processing by the CPU219.

[0150] Another output of the analog amplifier 213 is applied to adigitizer 216. The digitizer 216 converts the analog signal from theanalog amplifier 213 into a pulse width modulated digital signal. Onetype of digitizer is described in U.S. Pat. No. 4,360,798. Circuits suchas those contained in digitizer 216 have variable threshold levels whichcan be appropriately adjusted. The digitizer control unit 217 isconnected to the digitizer 216 and functions to effect the appropriateadjustment of threshold levels in the digitizer 216 in response tocontrol signals applied to the control unit 217 by the CPU 219 over thecontrol bus 226.

[0151] The output of the digitizer 216 is applied to an edge detector218. The operation of the edge detector 218 can be explained withreference to the discussion in co-pending U.S. Ser. No. 07/897,835 withrespect to corresponding component 118 in that application.

[0152] The edge detector 218 is connected to the decoder 220, whichfunctions in the manner described in the background of the invention.

[0153] More specifically, the decoder may operate as follows. First, atimer/counter register (which may be in the CPU microprocessor 219) isreset to all zeros. Operating as a timer, the register is incrementedevery machine cycle until another digital bar pattern (DBP) transitionoccurs. Whenever a DBP transition occurs the value of the counter, orthe value 255 if an overflow had occurred, is transferred to anotherregister, and then into memory. The value of the register represents thenumber of machine cycles between DBP transitions, i.e., the pulse width.After the value of the register is transferred, it is once again resetto zeros and the incrementing process continues until the nexttransition.

[0154] At any time a bar or space may last for more than 255 countcycles. If this occurs a timer overflow interrupt is generated. The CPU219 may run an interrupt service routine in response to the interrupt.This routine sets a flag that is used at the next DBP transition toindicate that an overflow had occurred. The interrupt service routinealso checks whether the Start of Scan (SOS) signal has changed from itsstate at the beginning of this scan data acquisition process. If SOS haschanged, a value of 255 is written as the width of the last element andthe data acquisition process terminates. The end result is that asequence of words are stored in memory, with each 16-bit wordrepresenting, for example, the pulse width representing the successivebars and spaces detected by the bar code reader.

[0155] The decode algorithm operates on the data in memory as thefollowing exemplifies. First, right and left quiet zones are found bysearching the data in memory for spaces which are large in comparison toneighboring data elements. Next, the decode of each character proceeds,beginning from the element to the right of the left quiet zone. Thedecode process for each character is specific to each symbology.Therefore, different character decode algorithms may be applied if thedecoder is set to auto-discriminate code types. In general, the decodeapplies mathematical operations to calculate the number of unit modulesencoded in each element, or pairs of elements for so called “deltacodes” such as Code 128 and UPC. For so called “binary” codes, such asCode 39, the decoder applies mathematical operations to calculate athreshold between wide and narrow elements and then performs arelational comparison between each element and the threshold. Thethreshold is calculated dynamically, that is, the threshold is not thesame for all the elements.

[0156] The decoded data is stored in a latch 221 which is connected to adata bus 222. The latch 221 is also connected to a control bus 226 whichis also connected to the CPU 219.

[0157] In the preferred embodiment, the processing of either the pulsewidth data, or the decoded data, is implemented in software undercontrol of the CPU 219. The following discussion presents an example ofan algorithm that may be implemented in a computer program in the readeraccording to the present invention.

[0158]FIG. 14 is a flow chart of an algorithm according to the presentinvention that functions to determine whether a portion of a 1D or 2Dbar code symbol has been read, and whether the type or scanning to beused should be modified, or other parameters under control of thescanning system, such as the light level in the field of view, should beadjusted. It is assumed that certain predetermined initializationparameters are automatically set when the scanner is turned on, asrepresented by block 300. The scanner is then placed in an “interpret”mode (as opposed to a “read” mode) and the algorithm proceeds as shownin FIG. 14.

[0159] In accordance with FIG. 14, a scan is obtained in step 302 byscanning the field of view with a laser beam and detecting the reflectedlight with FIG. 13 detector 206. A determination is made in step 304 todetermine if a two-dimensional bar code has been scanned. If thedetermination is positive, the laser light source is deactivated in step306. The ambient light level is reviewed, typically against apredetermined threshold, in step 308. If the ambient light is sufficientto obtain a satisfactory read, the scan is processed through the decoderin step 310 and the results of the decoding are transmitted to thescanner in step 312 and the scan parameters modified in responsethereto, if appropriate. If, in step 308, it is determined that theambient light is insufficient to obtain a satisfactory read, then theLED is activated in step 314. The scan is then decoded and the decodingresults transmitted as described above. If, in step 304, it isdetermined that a one dimensional bar code has been scanned, the scan isdecoded in step 316 and the results of the decoding are transmitted tothe scanner in step 318 and the scan parameters modified in responsethereto, if appropriate. If desired, an ambient light level check:, asperformed in step 308, could also be performed for scans of onedimensional bar codes.

[0160]FIG. 15A is a perspective view and FIGS. 16A-16B a plan andelevation view of a hybrid scanner in accordance with a furtherembodiment of the present invention. A scan assembly including a laserdiode, optics and scan engine 401 emit a visible light beam 430. Thebeam is reflected from mirror 403 towards the targeted symbol which canbe a one dimensional bar code as shown or a more complex symbol such asa matrix array to geometric shapes. The scan assembly 401 produces avisible scanning light beam, such as a flying spot light beam, which,when directed off mirror 403, forms a scan line across the targetedsymbol. A charge coupled device (CCD) or other solid state imagingdevice 404, which includes an array of detection elements detects orimages reflected visible light 440 from the symbol towards which thevisible scanning light beam 430 from laser diode of assembly 401 hasbeen directed. The reflected light 440 passes through conventionaloptics 408 (as shown in FIGS. 16A and B) which are disposed in front ofthe CCD 404 detection element array. Optics 408 are automatically selffocussing, so as to adjust the focal point of the image on the array ofdetection elements. The visible light beam 430 is beneficially used toaim the scanner at the target. The CCD 404 reads the targeted symbolusing either reflected ambient light or the reflected light from thevisible light beam 430 or both.

[0161] Another feature of the present invention when operating in thescanning laser beam/scanning CCD detector mode is the correlation of thespeed of scanning of the laser beam with respect to the speed ofscanning by the CCD detector. In the preferred embodiment, the laserbeam is scanned at a much faster rate than the CCD is scanned. Thus theentire symbol is illuminated over a short period of time, and the entireCCD array integrates the light received over that period of time. Theeffect on the CCD is to produce an image equivalent to a narrow fixedbeam of light illuminating the symbol, such as described in the relatedpatent application entitled “Method and Apparatus for ReadingTwo-Dimensional Bar Code Symbols with an Elongated Laser Line.” Inanother embodiment, requiring more sophisticated digitizing and dataprocessing, the laser beam may be scanned much slower than the CCDdetector. In such an embodiment the laser spot ideally illuminates justone pixel of the CCD detector at a time. Thus, the reflectivity of thatpixel on the target becomes the principal signal response in the fieldof the view during a single scan by the CCD detector.

[0162] Since the appropriate scanning rate may not be known a priori,another feature and embodiment of the present invention is to slowlyvary the scanning rate (of either the scanning laser beam, or the CCDdetector, or both) over a predetermined range if the initial scanningrates do not result in symbol decoding. For example, the individualdetection elements can be scanned at a variable scanning rate under thecontrol of controller 415 which can be actuated, for example, by toggleswitch 417, or automatically by software implemented by processor 420,to change the scanning rate.

[0163] As shown, CCD 404 is a two-dimensional CCD camera. The scanengine is preferably small, for example, an SE-1000 scan enginemanufactured by Symbol Technologies, Inc. The CCD has a one-third inchtwo-dimensional array, preferably 500 by 500 pixels. The field of viewof the CCD is greater than 30 degrees and is plus or minus 20 degreesfor the one-dimensional laser scanner. The working range of the systemshown is approximately 4 to 10 inches for a MaxiCode, UPSCODE(TM) orone-dimensional UPC code.

[0164] A processor 420, including a conventional decoder 420 a and asymbol discriminator 420 b to determine if the symbol being read is ofthe particular symbology type, e.g. a matrix code such as a UPSCODE(TM)symbology, which the hybrid scanner is designed to read. The symboldiscriminator receives a signal corresponding to the electrical signalgenerated by the CCD which represents the sensed reflected light. Thesymbol discriminator 420 b implements an algorithm to determine if thereceived signal is of a type which the scanner is capable of decoding.If a “yes” determination is made, the signal is decoded by the decoder420 a. The symbol discriminator 420 b, for example, can be implementedusing a comparator circuit or other conventional means, to determine ifthe symbol conforms to the appropriate symbology type. Symboldiscriminator 420 b could, if desired, be replaced by software whichimplements the discrimination algorithm and is stored in the memory ofprocessor 420 as discussed above in connection with FIG. 14. If thetarget is determined to be a conforming symbol, the decoder 420 adecodes the signal and the decoded signal is transmitted to, forexample, a storage device, display or further processing circuitry asdiscussed above with reference to FIG. 13. If the target symbol isdetermined by the symbol discriminator 420 b to be of a non-conformingsymbology, the discriminator 420 b transmits a signal, for example, tothe deactivator 422 and the deactivator 422 in turn transmits a signalto deactivate the CCD 404 and, if desired, the scan assembly 401.

[0165] In operation, the FIG. 15A scanner is capable of reading a symbollocated within an approximate range of 4 to 10 inches from the scanninghead window 407 shown in FIGS. 16A and 16B. Although a laser diode isshown in FIGS. 15A and 16A-16B, a light emitting diode (LED) could bealternatively used. If an LED is used in lieu of a laser diode, thesymbology discriminator implements the algorithm shown in FIG. 14. Ineither configuration, an ambient light detector 405 can be used, asappropriate, to ensure that there is sufficient ambient light to obtaina proper read of the targeted symbol. The ambient light detector detectsthe ambient light in the field of view of the CCD. If the CCD is toimage ambient light, the visible light beam is used only for aiming ororientation. In such a case, if a desired threshold is met indicatingsufficient ambient light for a read, the laser diode is activated byactivator 406 to target the symbol. The activator 406 may also activatethe CCD, if not otherwise activated, to image the symbol. Alternatively,if reflected visible light from the emitted light beam will be detected,the ambient light detector 405 and activator 406 may be unnecessary. Asa third alternative, the CCD may be capable of sensing either reflectedambient light or reflected light from the visible light produced by thelaser or light emitting diode. In this case, the laser diode or LED areactivated only when an ambient light threshold level is not reached,indicating that the ambient light level is insufficient to obtain aproper read. The ambient light detector 405 and activator 406 are ofconventional design and can be implemented in any of a number of wellknown ways. It should be understood that the scanner of FIG. 15A couldinclude features described above in connection with the otherembodiments of the invention. The CCD sensor can also function as arange finder as described with reference to FIG. 18 below.

[0166]FIG. 15B depicts a somewhat altered configuration of the hybridscanner of FIG. 15A. The FIG. 15B configuration is particularly suitablefor reading dual symbols of different symbology types on a singlepackage. For example, as shown in FIG. 15B a UPC symbol 411 is locatedadjacent to a UPS code symbol 413. The UPC code 411 may, for example,encode information relating to the contents of the package while UPScode 413 may include customer and/or destination information.

[0167] The 15B configuration is identical to that of the FIG. 15Aembodiment except as noted below. A photodetector 409, such as aphotodiode, is included in the FIG. 15B configuration and is used todetect the reflection of light 440 from the scanning light beam 430 offthe UPC symbol 411. For reading two symbols on a single package, the CCD404 separately images the reflected light 440 from the UPS code symbol413. The reflected light imaged by the CCD 404 may be either ambientlight or light from the scanning light beam. The symbols are separatelyprocessed in the conventional manner. The processing may be performed,in whole or in part, within the scan unit as may be desirable for theapplicable application. The scanning beam scans across booth symbol 411and 413 and is used both for aiming and/or orienting the scan unit aswell as for producing the light which will be detected after reflectionfrom symbol 411. The light beam could be used, with respect to symbol413, solely for aiming/orienting purposes. However, the light beam couldalso be used for reading the symbol 413.

[0168] A processor 420, identical to that described with reference toFIG. 15A above, includes a conventional decoder 420 a and symboldiscriminator 420 b. The discriminator 420 b determines if the symbol413 being read by the CCD is of a particular symbology type, e.g. amatrix code conforming to UPSCODE(TM) symbology. Additionally, aprocessor 424, including a conventional decoder 424 a and symboldiscriminator 424 b, is provided to determine if the symbol 411 beingread by the photodiode 409 is of a particular symbology type, e.g. a barcode conforming to a UPC code symbology.

[0169] As described with reference to the FIG. 15A scanner, the symboldiscriminator 420 b receives a signal corresponding to an electricalsignal generated by the CCD 404, which in turn corresponds to the imagedreflected light off symbol 413. The received signal is transmitted tothe decoder 420 a if the symbol discriminator 420 b determines that thesymbol 413 confirms to the appropriate symbology type. If the target isdetermined to be a conforming symbol, the decoder 420 a decodes thesignal and transmits the decoded signal to, for example, a storagedevice, display or further processing circuitry. If the target symbol isdetermined by the symbol discriminator 420 b to be of a nonconformingsymbology, the discriminator 420 b transmits a signal to theactivator/deactivator 426 reflecting the non-conforming nature of thetarget and, in response, the activator/deactivator 426 may, for example,transmit a signal to deactivate the CCD 404 and also, if desired, thephotodiode 409. Activator/deactivator 426 is similar to deactivator 422of the FIG. 15A scanner but is adapted to include the capability toactivate and/or deactivate either or both of the CCD 404 and photodiode409.

[0170] The symbol discriminator 424 b receives a signal corresponding toan electrical signal generated by the photodiode 409, which in turncorresponds to the detected reflected light off symbol 411. The receivedsignal is transmitted to the decoder 420 a if the symbol discriminator424 b determines that symbol 411 conforms to the appropriate symbologytype. The symbol discriminator 424 b is similar to symbol discriminator420 b, and can use a comparator circuit, software or other conventionalmeans to implement the applicable algorithm. If the target is determinedto be a conforming symbol, the decoder 424 a decodes the received signaland transmits the decoded signal to, for example, a storage device,display or further processing circuitry. If the target symbol isdetermined by the symbol discriminator 424 b to be of a non-conformingsymbology, the discriminator 424 b transmits a signal to theactivator/deactivator 426 reflecting the non-conforming nature of thetarget and, in response, the activator/deactivator 426 may, for example,transmit a signal to deactivate the photodiode 409 and also, if desired,CCD 404.

[0171] The FIG. 15C scanner, is an adaptation of the FIG. 15B scanner,which is particularly beneficial in operations where a single scannerwith dual modalities is required or desired. Such a need may arise, forexample, where different packages, each with a label which requiresscanning and conforms to one of two symbology types, are inventoried ina similar location, such as a warehouse, trailer, or retail outlet, orare being moved along a single conveyor.

[0172] In such cases, one symbol type, such as a UPS or other matrixcode, may be particularly suitable for imaging with CCD 404. Anothersymbol type, such as a bar code, may be more suitable for detection by aphotodetector 409. The reflection of ambient or emitted light off onetype of symbol may be used for imaging while the reflection of emittedlight off the other type of symbol may be used for photodetection. Theemitted light may, for example, be a flying spot visible light beamgenerated by a laser diode in scan assembly 401.

[0173] For such operations, as shown in FIG. 15C, both the CCD 404 andphotodiode 409 are directed to scan a single targeted symbol 430 whichmay be either a UPC code or a UPS code, or other types of symbolsconforming to differing symbology types. The CCD 404 images thereflection of visible ambient and/or emitted light off symbol 450. Thephotodiode 409 simultaneously detects the reflection of the flying spotlight beam emitted by assembly 401 from the symbol 450. Symboldiscriminators 420 b and 424 b respectively receive a signalcorresponding to the electrical signal generated by the CCD 404 and asignal corresponding to the electrical signal generated by thephotodiode 409. The respective signals are analyzed by symboldiscriminators 420 b and 424 b.

[0174] In this case, if the signal received by discriminator 420 b isdetermined by discriminator 420 b to conform to UPSCODE(TM) symbology,the signal is decoded by decoder 420 a and transmitted for storage,further processing, display or other operations, as appropriate. If, onthe other hand, the imaged symbol is determined not to conform toUPSCODE(TM) then a signal is sent to the activator/deactivator 426 whichaccordingly sends a signal to deactivate the CCD. Preferably the CCDremains deactivated until a signal is transmitted fromactivator/deactivator 426 to deactivate photodiode 409, at which timeactivator/deactivator 426 also transmits a signal activating CCD 404. Itwill be understood that the deactivation of photodiode 409 andactivation of CCD 404 will occur when a symbol subsequently targeted bythe scanner conforms to UPSCODE(TM) rather than UPC code symbology.

[0175] Likewise, if the signal received by discriminator 424 b isdetermined by discriminator 424 b to conform to UPC code symbology, thesignal is decoded by decoder 424 a and transmitted from decoder 424 afor storage, further processing, display or other operations, asappropriate. If, on the other hand, the detected symbol is determinednot to conform to the UPC code symbology then a signal is sent bydiscriminator 424 b to the activator/deactivator 426 which accordinglysends a signal to deactivate the photodiode 409. Preferably thephotodiode remains deactivated until a signal is transmitted fromactivator/deactivator 426 to deactivate CCD 404, at which timeactivator/deactivator 426 also transmits a signal activating photodiode409. Here it should be understood that the activation of photodiode 409and deactivation of CCD 404 will occur when a symbol subsequentlytargeted by the scanner is determined to conform to UPC code symbologyrather than the UPSCODE(TM) symbology.

[0176] If desired, only a single detector, i.e. either the CCD orphotodiode, could be initially activated. One or more indicators mightalso be provided to notify a user if the CCD or photodiode are active orhave been activated or deactivated. Each scanner will also typicallyinclude one or more digitizers for digitizing a signal corresponding toan electrical signal generated by the CCD or photodiode, as applicable,prior to symbol discrimination and decoding. Additional photodetectors,CCD's and processors could be added, with minor modifications to theactivator/deactivator 426, to provide for additional modalities andfurther flexibility in reading individual symbols which may be of anyone of three or more symbology types. Furthermore, theactivator/deactivator 426 could be eliminated if desired. In such aconfiguration, the CCD or photodiode could be selectively activated by,for example, a manual switching mechanism or could both be continuouslyactivated irrespective of the symbology type of the symbols beingtargeted during a particular time period.

[0177] Using the FIG. 15C system, the scanner operates in two distinctmodalities, one for reading bar code symbols and the other for readingmatrix codes. The symbol discriminators 420 b and 424 b determine if thetargeted symbol 430 is of a predetermined category or symbology type. Ifa signal is received by the activator/deactivator 426 from only one ofthe discriminators 420 b and 424 b, it indicates that the category ofthe targeted symbol necessarily conforms to the predetermined symbologytype acceptable to the other symbol discriminator. If signals arereceived by activator/deactivator 426 from both discriminators 420 b and424 b then the category of the targeted signal is necessarily outsidethe predetermined categories for the scanner. Hence, either of the twomodalities are selected in response to a signal received from one of thetwo symbol discriminators. In one modality the CCD is activated to readmatrix codes by imaging reflected ambient and/or emitted light. In theother modality the photodiode is activated to read bar codes, such asstacked bar codes or adjacent rows of linear bar codes, using emittedlight, perhaps in the form of a flying spot light beam, reflected offthe symbol.

[0178]FIG. 17 depicts a single scan line capable of being generated bythe scanner of FIGS. 15A, 15B and 15C across a UPS symbol formed with amatrix array of geometric shapes. By using a modified scan assembly 401other scan patterns could be formed. For example, if desired a scannerassembly could be substituted which would generate a raster,omni-directional or other scan pattern.

[0179] FIGS. 18A-18D depict various aspects of the range finder whichmay be included in any of the above described embodiments of theinvention. Range finders are typically included in devices such as autofocus type cameras. As shown, the sensor array 1600, such as a CCDarray, and lens 1602 sense the movement and position of the imageproduced by the scanning light beam 1604 as the distance between thesymbol 1660 and the scanner 1650 increases or decreases. No secondarylight source is required for range finding. A positive sensitive sensorcould be used in lieu of sensor array 1600 if desired. The results ofthe range finding can be used in an algorithm, such as that describedwith reference to FIG. 14 above but directed to modify the scanparameters if the distance between the scanner 1650 and the symbol 1660reach a predetermined threshold. For example, if a threshold isexceeded, it may be beneficial to activate an LED, even if the ambientlight level appears to be sufficient to obtain a satisfactory scan. Itmay also be advantageous to adjust the characteristics of the opticalcomponents, as discussed with reference to FIG. 13, as the distancereaches one or more predetermined thresholds.

[0180] The operation of the range finder will now be described withreference to FIGS. 18B-18D. As shown the scanner 1650 has a field ofview (FOV). The scan line image detected by the sensor array 1600 has alength d₃ when the targeted symbol 1660 is a distance d from the scanner1650. On the other hand, when the symbol 1660 is a distance d₂ which isgreater than the distance d₁, from the scanner 1650, the scan line imagedetected by the CCD 1600 has a length of d₄ which is greater than d₃.Thus, the length of the scan line image detected by the sensor array1600 can be used to determine the distance of the scanner 1650 from thetarget symbol 1660. Once the length of the image is determined, it can,for example be compared in a comparator circuit, by softwareimplementing an appropriate algorithm, or using other conventionalmeans, to correlate the length of the detected image with a distance orrange of the symbol.

[0181]FIG. 19A depicts a simplified sectional side view of a gun-shapedhousing for a hybrid scanner of the type shown in FIGS. 15A, 15B or 15C.Gun-shaped housing 500 has a narrow body 501 and single window 502through which the light beam is emitted and reflected light from thetarget enters the gun housing 500. A trigger switch 503 is provided foractivating the scan assembly and detector, or detectors, and othercomponents within the housing. The housing can house the processor 420and other components described above, if provided. A battery 504provides the power to the various components when the trigger 503 issqueezed. Conventional processing circuitry 512 is provided to generatea signal corresponding to the electrical signal generated by the sensor404, and detector 409 (not shown) which is suitable for transmission bywireless transmitter 514 to a remote receiver 516 at, for example acentral processing or electronic data storage device 518. Thetransmitter could if desired be a transceiver and might operate at radioor other frequencies which are suitable for accomplishing thetransmission. The processing circuitry 512 includes an integrator 512Awhich processes the outputs of the individual detection elements of theCCD 404 into a single output signal prior to transmission.

[0182]FIG. 19B depicts a perspective view of the gun-shaped scanner ofFIG. 19A connected to a decode module 505 by a flexible cable 506. Inthis configuration, most, if not all, signal processing components andcircuitry are located in the decode module rather than the gun-shapedhousing. Electrical signals generated by the CCD 404 and/or photodiode409 of FIGS. 15A-15C, or signals corresponding thereto, are transmittedfrom the gun-shaped housing 500 over the flexible cable 506 to thedecode module 505. The decode module processes the received signal,preferably converting the received signal into a digitized signal anddecoding the signal to obtain information representing the spatialintensity variations of the target. The decoded information can then betransmitted by way of communication cable 507 to a base computed 508where the decoded information may be stored and/or further processed.Rather than a wire communication link 507, module 505 and computer 508can be beneficially provided with transmitter or transceiver 509 andreceiver or transceiver 510 to facilitate wireless communication of thedecoded and other information. If transceivers are provided, a two-waycommunication link can be established such that information andinstructions from computer 508 can, additionally, be transmitted todecode module 505.

[0183]FIG. 20 depicts a goose head type stationary mount 520 whichincludes a flexible cantilevered portion 521 attached to a stabilizingbase 522 and having a hybrid scanner housing portion 523 in which ahybrid scanner of the type shown in FIG. 15A, 15B or 15C is housed. Theflexible cantilevered support member 521 can be adjusted to increase ordecrease the distance between the housing 523 and the target. It alsoprovides the flexibility to direct the emitted light in virtually anydesired direction. The housing 523 can be fully rotated, i.e. 360°,around the base 522. As will be understood by those familiar with theart, the housing 523 can be directed to provide a light beamsubstantially parallel or perpendicular to the support structure 524upon which the base 522 rests. Although a particular shape of housing523 is depicted in FIG. 20, the housing shape could be in any desiredform so long as one or more windows are placed in the housing whichallow the emitted light beams and the reflected light from the target topass in and out of the housing. Additionally, in lieu of housing 523, amount (not shown) could, if desired, be provided on the end of theflexible cantilevered member 521 so as to accept the handle portion of,for example, the gun-shaped housing of FIG. 19A. Such a configurationwould allow a hybrid scanner in a gun-shaped housing to be utilized bothas a portable scanner and as a stationary scanner depending on theparticular need.

[0184] FIGS. 21A-21C depict hybrid scanners of the type shown in FIGS.15A, 15B or 15C arranged as part of a tunnel scanning system. Thesupporting structure 530 supports multiple hybrid scanners 531. Thescanners are arranged to scan symbols on packages moved along on aconveyor belt 532. The scanners are arranged and oriented in a precisemanner so as to facilitate the reading of symbols no matter whatorientation the package may be in as it moves along on the conveyor belt532. As perhaps best shown in FIGS. 21B and 21C, the conveyor belt 532is preferably made of a light transparent material so that scancomponents 531 can be located below the conveyor belt to read symbolswhich having an orientation opposed to the surface of the conveyor belt.Additionally, hybrid scanners are also supported so as to read symbolswhich are on an upstream or downstream face of a package during theirmovement through the tunnel scanning system.

[0185]FIG. 22 depicts a further tunnel scanner embodiment particularlysuitable for locating and tracking packages being transported by truck.As shown, hybrid scanners 531 are supported around the opening in thetrailer portion 541 of the truck 540. The scanning system can, forexample, be activated upon opening the trailer door on the rear of thetrailer portion 541. The hybrid scanners surround the opening and areoriented in a precise manner to provide a combined field of view whichwill allow a symbol located on a package being moved through theopening, for example, on slide 542 to be read no matter how the symbolmay be oriented at the time it moves through the opening. If desired, aProcessor 543 and wireless transmitter or transceiver 544 can be mountedin the trailer portion 541 or elsewhere within truck 540 to processsignals corresponding to an electrical signal generated by the CCD orphoto detector of the hybrid scanner which obtains the read. Theprocessed signal can if desired be communicated by wirelesstransmitter/transceiver 544 to a base station where the processed datais stored or utilized, for example, in notifying the owner of the goodsbeing transported that shipment has begun or delivery has occurred.Processor 543 may also, if desired, include a storage device for storingthe decoded information.

[0186]FIG. 23 shows a further application of a tunnel type scanningsystem utilizing the hybrid scanners of FIGS. 15A, 15B or 15C. Similarto the system shown in FIG. 22, hybrid scanners 531 are supported aroundan opening provided in the aircraft 550. The scanners are preciselyoriented to provide an acceptable combined field of view such that thetarget symbol on the package can be satisfactorily read no matter whatthe orientation of the package as it moves through the opening enclosedby the tunnel scanning system. If desired, a processor 543 and wirelesstransmitter or transceiver 544, of the type described in FIG. 22, canalso be provided.

[0187] Although certain embodiments of the invention have been discussedwithout reference to the scanner housing, triggering mechanism and/orother features of conventional scanners, it will be understood that avariety of housing styles and shapes and triggering mechanisms could beused. Other conventional features can also be included if so desired.The invention is directed primarily to a portable hand-held scanningdevice and tunnel type scanner system, and thus is preferablyimplemented using miniaturized components such as those described hereinor in the materials referenced herein, or otherwise known in the art.However, the scanner of the present invention is not limited to use inportable devices or tunnel type scanner systems and can also be easilyadapted for use in any housing which might be desirable or required fora particular application.

[0188] Additionally, even though the present invention has beendescribed with respect to reading one or two-dimensional bar code andmatrix array symbols, it is not limited to such embodiments, but mayalso be applicable to other indicia scanning or data acquisitionapplications. It is conceivable that the method of the present inventionmay also find application for use with various machine vision or opticalcharacter recognition applications in which information is derived fromindicia such as printed characters or symbols, or from the surface orconfigurational characteristics of the article being scanned.

[0189] In all of the various embodiments, the elements of the scannermay be implemented in a very compact assembly or package such as asingle printed circuit board or integral module. Such a board or modulecan interchangeably be used as the dedicated scanning element for avariety of different operating modalities and types of data acquisitionsystems. For example, the module may be alternately used in a hand-heldmanner, a table top goose neck scanner attached to a flexible arm ormounting extending over the surface of the table or attached to theunderside of the table top, or mounted as a subcomponent or subassemblyof a more sophisticated data acquisition system such as a tunnel scannersystem.

[0190] Each of these different implementations is associated with adifferent modality of reading bar code or other symbols. Thus, forexample, the hand-held scanner is typically operated by the user“aiming” the scanner at the target; the table top scanner operated bythe target moved rapidly through the scan field, or “presented” to ascan pattern which is imaged on a background surface. Still othermodalities within the scope of the present invention envision thearticles being moved past a plurality of scan modules oriented indifferent directions so at least the field of view allows one scan of asymbol which may be arbitrarily positioned on the article.

[0191] The module would advantageously comprise an optics subassemblymounted on a support, and an image sensor component. Control or datalines associated with such components may be connected to an electricalconnector mounted on the edge or external surface of the module toenable the module to be electrically connected to a mating connectorassociated with other elements of the data acquisition system.

[0192] An individual module may have specific scanning or decodingcharacteristics associated with it, e.g. operability at a certainworking distance, or operability with one or more specific symbologiesor printing densities. The characteristics may also be defined throughthe manual setting of control switches associated with the module orautomatically. The user may also adapt the data acquisition system toscan different types of articles or the system may be adapted fordifferent applications by interchanging modules in-the data acquisitionsystem through the use of a simple electrical connector.

[0193] The scanning module described above may also be implementedwithin a self-contained data acquisition system including one or moresuch components as keyboard, display, printer, data storage, applicationsoftware, and data bases. Such a system may also include acommunications interface to permit the data acquisition system tocommunicate with other components of a local or wide area network orwith the telephone exchange network, either through a modem or an ISDNinterface, or by low power radio broadcast from a portable terminal to astationary or mobile receiver.

[0194] It will be understood that each of the features described above,or two or more together, may find a useful application in other types ofscanners and readers differing from the types described above.

[0195] As described above, an improved indicia reader without thelimitations of prior art readers is provided. The indicia reader iscapable of providing an elongated scan line across indicia located closeto the scanner head. The reader can read one or two-dimensional or evenmore complex indicia. The reader is also capable of being aimed ororiented while imaging the indicia. Laser scanning with CCD imaging isprovided. The reader is capable of reading indicia of differentsymbology types including indicia comprised of a matrix array ofgeometric set shapes such as UPSCODE(TM).

[0196]FIG. 25 is a perspective view of a retroreflective scannerembodiment for scanning a bar code symbol 600 along a scan direction 602(shown as a horizontal line), the symbol having bars and spaces, eachbar extending along a transverse direction (shown as a verticaldirection) which is generally perpendicular to the scan direction.

[0197] The embodiment of FIG. 25 includes a light source comprising alinear array of light emitting diodes 604 arranged along the transversedirection and/or a linear array of laser diodes 606 also arranged alongthe transverse direction and parallel to the array of diodes 604.Preferably, the light emitting diodes 604 emit white light, and thelaser diodes 606 emit red light.

[0198] The light emitted by diodes 604 and/or 606 is focused by afocusing lens 608 and impinges on a stationary folding mirror 610 forreflection through an aperture 612 in a collection mirror 614 to anoscillatable scan mirror 616. The folding mirror 610 could beeliminated, but provides for a compact optical path. The scan mirror 616is a flat, planar mirror that is alternately and repetitively moved inopposite circumferential directions relative to the axis 618. The scanmirror 616 reflects the light impinging thereon to the symbol in a scanpattern, typically a scan line.

[0199] Light is reflected from the symbol to the scan mirror 616 andreflected to the apertured collection mirror 614, which is curved tocollect the returning light and direct it to a sensor. The sensor is afirst linear array of solid state detector cells 620 of monochromaticsensitivity and/or a second linear array of solid state detector cells622 of color sensitivity. Each array of cells 620, 622 is a chargecoupled device. The arrays of cells 620, 622 are arranged adjacent andparallel to each other. Each array of cells 620, 622 extends along thetransverse direction. Each sensor array of cells 620, 622 isindependently or cooperatively operative for detecting the intensity ofcollected light impinging on a respective cell, and for generating anelectrical signal indicative of the symbol 600.

[0200] In operation, the sensor array of cells 620 is particularlyadvantageous in detecting symbols printed with black bars against awhite background, whereas the sensor array of cells 622 is more usefulin detecting symbols printed in a color other than black. The use of twosuch sensor arrays reduces chromatic aberrations and the prior artinability to decode red-colored symbols. The scan rate of each sensorarray is preferably optimized to the desired resolution of the symbol.

[0201] If desired, the symbol is illuminated by either or both of thearrays of cells 604, 606. The intensity of the illumination is relatedto the ambient light level, and the choice of the array is related tothe color of the symbol being illuminated. The number of cells in eacharray of cells 604, 606 can also be controlled. The use of two lightemitting arrays helps reduce aiming parallax errors and also assists inreading poorly printed symbols.

[0202] It will be understood that each of the elements described above,or two or more together, also may find a useful application in othertypes of constructions differing from the types described above.

[0203] While the invention has been illustrated and described asembodied in an apparatus and method for reading indicia using chargecoupled device and scanning laser beam technology, it is not intended tobe limited to the details shown, since various modifications andstructural changes may be made without departing in any way from thespirit of the present invention.

[0204] Without further analysis, the foregoing will so fully reveal thegist of the present invention that others can, by applying currentknowledge, readily adapt it for various applications without omittingfeatures that, from the standpoint of prior art, fairly constituteessential characteristics of the generic or specific aspects of thisinvention and, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

[0205] What is claimed as new and desired to be protected by LettersPatent is set forth in the appended claims.

We claim:
 1. A device for electro-optically reading a bar code symbolhaving bars and spaces of different light reflectivity arrangedsequentially and spaced apart along a scan direction, each bar extendingvertically along a transverse direction that extends generallyperpendicular to the scan direction, the device comprising: a) a lightsource for generating a light beam; b) an optical element for directingthe light beam toward the symbol for reflection therefrom; c) a scannerfor scanning the light beam along the scan direction; and d) a lineararray of solid state detector elements arranged along the transversedirection, for detecting return light reflected from the symbol over afield of view, and for generating an electrical signal representing thesymbol.
 2. The device of claim 1, wherein the linear array is composedof charge coupled device cells.
 3. The device of claim 2, wherein thecells have monochromatic sensitivity.
 4. The device of claim 2, whereinthe cells have color sensitivity.
 5. The device of claim 1, wherein thelight source is a laser.
 6. The device of claim 5, wherein the laser iscomposed of a linear array of laser diodes arranged along the transversedirection.
 7. The device of claim 1, wherein the optical element is anoscillatable scan mirror for reflecting the light beam directly to thesymbol, and also for directly receiving the return light from thesymbol, and comprising a collection mirror for collecting the returnlight reflected off the scan mirror and for reflecting the collectedreturn light to the array of solid state detector elements.
 8. Thedevice of claim 7, wherein the collection mirror has an aperture, andwherein the light beam from the light source is directed through theaperture en route to the scan mirror.
 9. A device for electro-opticallyreading a bar code symbol having bars and spaces of different lightreflectivity arranged sequentially and spaced apart along a scandirection, each bar extending vertically along a transverse directionthat extends generally perpendicular to the scan direction, the devicecomprising: a) a linear array of light emitting elements arranged alongthe transverse direction, for generating a light beam; b) an opticalelement for directing the light beam toward the symbol for reflectiontherefrom; c) a scanner for scanning the light beam along the scandirection; and d) a detector for detecting return light reflected fromthe symbol over a field of view, and for generating an electrical signalrepresenting the symbol.
 10. The device of claim 9, wherein the lightemitting elements are diodes.
 11. The device of claim 9, wherein thelight emitting elements are lasers.
 12. The device of claim 9, whereinthe detector is a linear array of solid state detector elements arrangedalong the transverse direction.
 13. A bar code reader, comprising: apair of linear arrays of solid state detector elements arranged adjacentand parallel to each other, each of the arrays being operative fordetecting return light reflected from a bar code symbol over a field ofview, and for generating an electrical signal representing the symbol.14. The reader of claim 13, wherein one of the arrays is aone-dimensional array of charge coupled device cells with monochromaticsensitivity.
 15. The reader of claim 13, wherein one of the arrays is aone-dimensional array of charge coupled device cells with colorsensitivity.
 16. The reader of claim 13, and further comprising a whitelight source of light emitting elements for illuminating the symbol. 17.The reader of claim 13; and further comprising a scanner for scanning alight beam in a scan direction across bars and spaces of the symbol,each bar extending along a transverse direction that extends generallyperpendicular to the scan direction; and wherein each of the arrays isarranged along the transverse direction.